This modifies the edx_ansible role to dump a clean var
file on disk that can be used for subsequent update runs
so that config vars will not be lost

also changes the ansible tmp directory to /var/tmp which is a better
location than using $HOME (used for debugging mostly)

* Created new directory structure outlined in the README
* Created the LMS role which for now just creates teh application config
files
* Created the common role
* Updated the cf playbook to accept arguments