Parameterizing edx git repository location

* Creates global variable $platform_code_dir to store
  /opt/wwc/edx-platform, to replace the semihardcoded /opt/wwc/mitx that
  we had before.
* Plugs $platform_code_dir in a lot of different places
* Templatize sef's update script hack

Jarv/cleanup lms and examples

Feature/jrbl/tagging update install

* update tasks are meant to be the fast ones and the ones we want to be
  sure to always do (directory creations, permissions, etc.)
* install tasks are all the really slow things, like the git repo clone
  and package installations
* Every task can by run by --tags=install,update - which is the same as
  having no tags at all.

Conflicts:

	playbooks/roles/lms/tasks/main.yml

Jbau upstart restart handler

Jbau/lms preview

Use the new mitx repo locale

Nginx log reconfiguration

cleaning up old group_vars files

Documentation improvements, separation of phases, moving toward not usin...

* sends logs to /mnt/logs/nginx instead of /var/log. Note that on fresh
  server startup, nginx will still log to /var/log until it reads its
  configuration.
* Installs logrotate configuration for freshly moved nginx logs
* Some directory and file permissions fixups
* Improved order of operations on nginx installation/bringup

Configure logrotate to treat edx logs appropriately

* Bugfix to rsyslog configuration; configuration file had missing
  extension
* Logrotate recipes for edx log files
* Files reorganized, renamed

temporary software update script

comment out lms env vars that should be demo only

Configure rsyslog to catch logs from edx

* Touches directories and files into existence expected during setup for
  LMS and CMS
* Configures rsyslog to catch local0 and local1 from edx, and route into
  the appropriately named files in the appropriately named
  subdirectories
* Permissions updates to ensure rsyslog can write everywhere it's
  supposed to
* Restarts rsyslog after reconfiguration is complete

Until we get proper software updates working we need a script we can run
to orchestrate installs -- checkouts, collectstatic, restarts.  Tagged
with the "update" tag.  Just puts the file out there for now, doesn't
actually do any updates, that should be done with something like this:
    ansible GROUPNAME -i ./ec2.py -c ssh -s -a edx-update.sh

Jbau/cms