Fixed Typo

Remove the `update_templates command from the installation script, this
command was removed by
https://github.com/edx/edx-platform/commit/3722685e1a185ff4a0a085bb380ed793cf6d1e59

Some parts of the `create-dev-env/sh` script use `$WORKON_HOME` and
others hardcode `$HOME/.virtualenvs` which means if you **don't** put
your virtualenvs under `$HOME/.virtualenvs`, the script doesn't work at
all.

This commit removes the hardcoding of virtualenv location and
consistently uses `$WORKON_HOME` everywhere.

Since the output is passed through tee, when the django admin asks the
user if he would like to create a super user account, it blocks the
install, without even showing the question.

Disabled interactivity for syncdb.

Added options to make the output of `apt-get` and `mkvirtualenv`
friendlier to getting logged. This allows to be more easily recorded in
log files or when the install is performed through utilities - like
Vagrant.

The options passed to curl were not always the same - added logging of
error (-S) everywhere (was only used for Mac before) and made it quiet
in the rare few cases where it wasn't yet (-s).

The script used to download the latest version of ruby through rvm, then
later on install the one used by the project. Now we directly download
the version of the project when rvm is installed.

Added several options to the `create-dev-env.sh` script to improve its
ability to be used by another script:

* -y -- non interactive mode (no prompt, proceed immediately)
* -n -- do not attempt to pull edx-platform
* -q -- be more quiet (removes info at beginning & end)

This will be used, in particular, for Vagrant provisioning.

in line 470, changed "curl -O" to "curl -OL" such that the scripts runs without problems.

   Accepts any dirname for the edx-platform repo. Allows the script to be
   called from any directory, not just $BASE/edx-platform.

2 changes:
[1] If PROJECT_HOME is not set, AND create-dev-env.sh is run from a cloned repo, then set BASE to that repo;
else:  (and only finally) set BASE to a default of "$HOME/edx_all"

[2] if PROJECT_HOME is set, or if this is from a repo, don't add edx_all to the BASE name (no need;)

Added note about the current state of support for debian based systems to accurately reflect state of development