Feanil/monitor repos

We never used this function.

If we already have an AMI for a particular configuration, use that instead of
requesting a new one.

abbey.py - python script for creating AMIs in the VPC environment

only download ora when it hasn't already been downloaded

Devstack enables prereq install by default

Fix DNS issue on Ubuntu 12.10

abbey.py will launch an instance into a VPC, run ansible on it
and monitor it for updates using an SQS queue.  At the end of
the ansible run it will create an AMI and terminate the instance.

Lowered ORA minimum submissions for ML and peer grading

Updated devstack role to include ORA

Configure NLTK_DATA environment variable for ORA celery workers

This converts lms-preview variant to supervisor

and adds a clause to rake not to gather assets as it fails