change quoting for hash and adding ENGINE to DATABASES

Updated mongo role to be more flexible for different deployment scenarios

Added host parameter in the testing process of forum role

making lms/preview/cms ports env vars

Ensure the xqueue user and home directories exist.

Jarv/edxapp mixedmodule

Consolidate requirements.txt into a single file.

Stop referencing non-existent vars file.

Feanil/flatten vars

edx-west prod: don't install notifiers yet

The notifier isn't ready yet, needs theming to be done before it can be
installed.

edx-west: toggle carnegie institute to prod

Notifier config improvements: db dir, email vars

Added task to make sure elasticsearch is started

Allow configuration of IP Address of app servers to listen on

Modified vagrant-fullstack by using sandbox role definitions - Tested

rabbitmq-atp-update: Fixes "Failed to find required executable rabbitmq-plugins"

Forum role port test now properly uses host argument

- specify notifier_db_dir as a setting.  Had previously just stuck
  under $HOME, but Jim preferred as a distinct setting.

- pass through email settings env variables

- plumb through django's EMAIL_USE_TLS setting.  Required to be
  able to send mail using Amazon SES.  They speak smtp, but only
  over TLS.