SSL for communication between keystone and rabbitmq

Currently, Keystone can not be configured via Puppet to communicate with
rabbitmq using SSL. Most other puppet component already have this feature.
This commit enable this feature for Keystone.

Change-Id: Idd207a58a71c001e581d17c5b97965189e20869f
Use secret parameter for rabbit_password

Rabbit_password configuration was not using secret parameter so it
was visible on the logs.

Change-Id: Idad892f0c461fce53eaa81ec8a7f3cfe871a9d00
Closes-Bug: 1328448
Allow blank email address for keystone_user type

Adjust the newvalues() regex to allow for a blank string for the email
parameter to keystone_user resources.

Change-Id: I36b3eb54fcc39f810861f217dcf1b02e58265aef
Closes-Bug: #1319464