OPS-1593 As an operator, I want sudo_user converted to become user in roles and plays, for compatibility with Ansible 2.x

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)

abbey.py will launch an instance into a VPC, run ansible on it
and monitor it for updates using an SQS queue.  At the end of
the ansible run it will create an AMI and terminate the instance.

Also renaming the deploy_* plays to the play name