Merge pull request #1034 from edx/jarv/clean-ami

Jarv/clean ami
Preview module store.
Adding mapping for preview host.
Removing preview hash gen.
removing preview runtime config.
Deleting legacy templates.
removing unused config.
should be a dict.
Merge pull request #1040 from edx/e0d/preview

E0d/preview
Remove the repo.txt requirements file.
Merge pull request #1125 from edx/feanil/repo_req_release

Feanil/repo req release
updated edxapp ansible role to include the ability to enable third party authorization
make backup of previous server-vars.yml
Play to create the analytics db and users
using pip to install mysql lib
Update main.yml

To use local mongodb repo
Update main.yml

To use local mongodb repo
Made more generic
Change the variables 

Change the variables to MONGODB_APT_KEY and MONGODB_REPO
Change the variables

Change the variables to MONGODB_APT_KEY and MONGODB_REPO