forum role cleanup

* consistent jinja variable syntax
* comment blocks on the tasks/main.yml files
* some syntax errors, variable name issues
* indenting, breaking up long lines
* various bug fixes
adding edx-sandbox
fixing mixxing forum_mongo_database var definition
typo in var name
api_id -> api_key
changing edxapp defaults for comments service
resolving merge conflicts
fixing typo
Merge remote-tracking branch 'origin/e0d/upstart-source-env' into jarv/forum-cleanup
Merge pull request #180 from edx/jarv/forum-cleanup

forum role cleanup