Install NLTK for edxapp workers

updating newrelic, dd, splunk flag names

Add dependencies for edxapp and ora on the NLTK role
Install minimal NLTK data used by EASE

Add celery flower role

Link course data to location where edxapp looks for code.

The application looks for course code inta a directory named after the
course name so we are symlinking the course repo to that directory as
well.

Adding port 587 for SMTP to InboundSMTPPublicNetworkAclEntry and NATSecurityGroup

Initial commit, works for happy path.

Adding tags arg for ansible

Be more explicit when failed to connect on sqs or ec2

add a test play for testing rolling deploys

updating the commoncluster plays so that they can be run from jenkins

removing discern from cont integration

Add thin-backup plugin

Update to no longer track repo.txt

Gems for everyone.

Although this can be used as part of any DR strategy, the immediate intent is
providing an ability to quickly spin up Jenkins master instances for testing
against. (A user would run the ansible script to create a test instance,
then restore backup .zip which would contain all of the jobs' and master's
configuration.)

ThinBackup plugin doc: https://wiki.jenkins-ci.org/display/JENKINS/thinBackup

Update README.md

updating abbey to use a deployment.yml var file