Updating dev environment setup

* Script now installs RVM in conventional location (~/.rvm) by
  default, though it allows for the override if desired. This will
  enable folks to install edX alongside other Ruby projects also
  using RVM.
* Script now uses virtualenvwrapper to ease the process of enabling
  the edX virtualenv and to allow for easy switching back and forth
  between virtualenv projects. It now also installs the "mitx"
  virtualenv in the conventional location of ~/.virtualenv.
* Adding a .rvmrc file so that the Ruby environment will be
  automatically activated (via `rvm use`) whenever the user hits
  the `mitx/` directory.

.rvmrc

+rvm use 1.9.3-p374@mitx

create-dev-env.sh

@@ -26,12 +26,15 @@ EOL
     printf '\E[0m'
 
 }
+
 error() {
       printf '\E[31m'; echo "$@"; printf '\E[0m'
 }
+
 output() {
       printf '\E[36m'; echo "$@"; printf '\E[0m'
 }
+
 usage() {
     cat<<EO
 
@@ -47,11 +50,10 @@ EO
 }
 
 info() {
-
     cat<<EO
     MITx base dir : $BASE
-    Python dir : $PYTHON_DIR
-    Ruby dir : $RUBY_DIR
+    Python virtualenv dir : $PYTHON_DIR
+    Ruby RVM dir : $RUBY_DIR
     Ruby ver : $RUBY_VER
 
 EO
@@ -85,7 +87,7 @@ clone_repos() {
         if [[ -d "$BASE/data/$REPO" ]]; then
             mv "$BASE/data/$REPO" "${BASE}/data/$REPO.bak.$$"
         fi
-	cd "$BASE/data"
+        cd "$BASE/data"
         git clone git@github.com:MITx/$REPO
     fi
 }
@@ -93,20 +95,30 @@ clone_repos() {
 ### START
 
 PROG=${0##*/}
-BASE="$HOME/mitx_all"
-PYTHON_DIR="$BASE/python"
-RUBY_DIR="$BASE/ruby"
-RUBY_VER="1.9.3"
-LOG="/var/tmp/install-$(date +%Y%m%d-%H%M%S).log"
 
+# Adjust this to wherever you'd like to place the codebase
+BASE="${PROJECT_HOME:-$HOME}/mitx_all"
 
-# Read arguments
+# Use a sensible default (~/.virtualenv) for your Python virtualenvs
+# unless you've already got one set up with virtualenvwrapper.
+PYTHON_DIR=${WORKON_HOME:-"$HOME/.virtualenv"}
+
+# RVM defaults its install to ~/.rvm, but use the overridden rvm_path
+# if that's what's preferred.
+RUBY_DIR=${rvm_path:-"$HOME/.rvm"}
 
+LOG="/var/tmp/install-$(date +%Y%m%d-%H%M%S).log"
+
+# Make sure the user's not about to do anything dumb
 if [[ $EUID -eq 0 ]]; then
     error "This script should not be run using sudo or as the root user"
     usage
     exit 1
 fi
+
+# TODO: test for an existing virtualenv
+
+# Read arguments
 ARGS=$(getopt "cvhs" "$*")
 if [[ $? != 0 ]]; then
     usage
@@ -236,31 +248,71 @@ clone_repos
 
 bash $BASE/mitx/install-system-req.sh
 
+output "Installing RVM, Ruby, and required gems"
+
+# If we're not installing RVM in the default location, then we'll do some
+# funky stuff to make sure that we load in the RVM stuff properly on login.
+if [ "$HOME/.rvm" != $RUBY_DIR ]; then
+  if ! grep -q "export rvm_path=$RUBY_DIR" ~/.rvmrc; then
+      if [[ -f $HOME/.rvmrc ]]; then
+          output "Copying existing .rvmrc to .rvmrc.bak"
+          cp $HOME/.rvmrc $HOME/.rvmrc.bak
+      fi
+      output "Creating $HOME/.rvmrc so rvm uses $RUBY_DIR"
+      echo "export rvm_path=$RUBY_DIR" > $HOME/.rvmrc
+  fi
+fi
+
+curl -sL get.rvm.io | bash -s -- --version 1.15.7
 
-# Install Ruby RVM
+# Ensure we have RVM available as a shell function so that it can mess
+# with the environment and set everything up properly. The RVM install
+# process adds this line to login scripts, so this shouldn't be necessary
+# for the user to do each time.
+if [[ `type -t rvm` != "function" ]]; then
+  source $RUBY_DIR/scripts/rvm
+fi
 
-output "Installing rvm and ruby"
+# Ruby doesn't like to build with clang, which is the default on OS X, so
+# use gcc instead. This may not work, since if your gcc was installed with
+# XCode 4.2 or greater, you have an LLVM-based gcc, which also doesn't
+# always play nicely with Ruby, though it seems to be better than clang.
+# You may have to install apple-gcc42 using Homebrew if this doesn't work.
+# See `rvm requirements` for more information.
+case `uname -s` in
+    Darwin)
+        # TODO (Nate): test to see if CC is already set to gcc or something
+        #              similar first (not clang).
+        export CC=gcc
+        ;;
+esac
 
-if ! grep -q "export rvm_path=$RUBY_DIR" ~/.rvmrc; then
-    if [[ -f $HOME/.rvmrc ]]; then
-        output "Copying existing .rvmrc to .rvmrc.bak"
-        cp $HOME/.rvmrc $HOME/.rvmrc.bak
-    fi
-    output "Creating $HOME/.rvmrc so rvm uses $RUBY_DIR"
-    echo "export rvm_path=$RUBY_DIR" > $HOME/.rvmrc
+# Let the repo override the version of Ruby to install
+if [[ -r $BASE/mitx/.ruby-version ]]; then
+  RUBY_VER=`cat $BASE/mitx/.ruby-version`
 fi
 
-curl -sL get.rvm.io | bash -s -- --version 1.15.7
-source $RUBY_DIR/scripts/rvm
+# Current stable version of RVM (1.19.0) requires the following to build Ruby:
+#
+# autoconf automake libtool pkg-config libyaml libxml2 libxslt libksba openssl
+#
+# If we decide to upgrade from the current version (1.15.7), can run
+#
+# LESS="-E" rvm install $RUBY_VER --autolibs=3 --with-readline
+#
+# to have RVM look for a package manager like Homebrew and install any missing
+# libs automatically. RVM's --autolibs flag defaults to 2, which will fail if
+# any required libs are missing.
 LESS="-E" rvm install $RUBY_VER --with-readline
 
+# Create the "mitx" gemset
+rvm use "$RUBY_VER@mitx" --create
+
 output "Installing gem bundler"
 gem install bundler
 
 output "Installing ruby packages"
-# hack :(
-cd $BASE/mitx  || true
-bundle install
+bundle install --gemfile $BASE/mitx/Gemfile
 
 
 # Install Python virtualenv
@@ -274,16 +326,31 @@ case `uname -s` in
         ;;
 esac
 
+# virtualenvwrapper uses the $WORKON_HOME env var to determine where to place
+# virtualenv directories. Make sure it matches the selected $PYTHON_DIR.
+export WORKON_HOME=$PYTHON_DIR
+
+# Load in the mkvirtualenv function if needed
+if [[ `type -t mkvirtualenv` != "function" ]]; then
+  source `which virtualenvwrapper.sh`
+fi
+
+# Create MITx virtualenv and link it to repo
+# virtualenvwrapper automatically sources the activation script
 if [[ $systempkgs ]]; then
-    virtualenv --system-site-packages "$PYTHON_DIR"
+    mkvirtualenv -a "$BASE/mitx" --system-site-packages mitx || {
+      error "mkvirtualenv exited with a non-zero error"
+      return 1
+    }
 else
     # default behavior for virtualenv>1.7 is
     # --no-site-packages
-    virtualenv  "$PYTHON_DIR"
+    mkvirtualenv -a "$BASE/mitx" mitx || {
+      error "mkvirtualenv exited with a non-zero error"
+      return 1
+    }
 fi
 
-# activate mitx python virtualenv
-source $PYTHON_DIR/bin/activate
 
 # compile numpy and scipy if requested
 
@@ -315,6 +382,8 @@ case `uname -s` in
         # need latest pytz before compiling numpy and scipy
         pip install -U pytz
         pip install numpy
+        # scipy needs cython
+        pip install cython
         # fixes problem with scipy on 10.8
         pip install -e git+https://github.com/scipy/scipy#egg=scipy-dev
         ;;
@@ -344,14 +413,18 @@ cat<<END
    Success!!
 
    To start using Django you will need to activate the local Python
-   and Ruby environment (at this time rvm only supports bash) :
+   and Ruby environments. Ensure the following lines are added to your
+   login script, and source your login script if needed:
+
+        source `which virtualenvwrapper.sh`
+        source $RUBY_DIR/scripts/rvm
+
+   Then, every time you're ready to work on the project, just run
 
-        $ source $RUBY_DIR/scripts/rvm
-        $ source $PYTHON_DIR/bin/activate
+        $ workon mitx
 
    To initialize Django
 
-        $ cd $BASE/mitx
         $ rake django-admin[syncdb]
         $ rake django-admin[migrate]