unix sockets.

Change how abby gets notified.

We were previously using the jenkins api which was more complicated than the
buildByTokens plugin and its API.

Jarv/focaccia

Feanil/mckinsey abbey

These vars are also set by the jenkins job

runs the worker role before the edxapp role

Remove hash_behaviour=merge

Because the CMS uses the git hash of the edx-platform for the
static path it can be problematic if you update the edx-platform
repo for the worker AFTER you update the edx-platform repo
for edxapp.  When running the edxapp role in worker mode
rake gather_assets is skipped.

This is a workaround but we may want to consider using separate
repos for worker and edxapp for situations where both are installed
on the same server.

E0d/automating edxapp

updating vpc dns script to conform to the new dns scheme

* pep8 updates
* adding more comments
* refactoring
* adding examples

changing role to play

Make the DB version configurable and set it to 5.6 by default.