Add the ability to run plays on the leader in a tag group before running it on the rest.
Move to use the new role ec2 tag.
Leave only the forums related roles on the forums server.
Run user creation on condition.

Meant to be used in plays where we use the 'first_in_tag' host vars to only run usercreation on one machine.
Put overrideables in all caps.
Add the mongo plays.
Ensure instances are sorted.
Be able to override the mongo bind ip.
Update elb security groups to allow connections to default ports.
Update to prioritize instance role for ssh config naming.
Pull out forums settings that we may want to override.
Ensure supervisor starts before roles that depend on it are run.
Update elb forwarding rules.
Add migrations for xqueue and move to supervisor.
Add tags to the RDS.
Add a dns name to the rds.
Fix tag for rds.
Remove flush as it was causing other errors.
Have edx_vpc point to the CLODUFORMATION_STOCK_NAME variable.
Only restart apps.