rabbitmq - add support to configure plugins via config file

Pull in changes from:
  voxpupuli/puppet-rabbitmq#777

This allow us to configure plugins using the config file
(/etc/rabbitmq/enabled_plugins) and makes it possible to
enable the rabbitmq_management plugin without also
downloading and installing rabbitmqadmin.

Change-Id: I3c714c5f1a800b9047533ca1a3f9feab42b575e4
Related-Bug: #1815675

tags/stein-py3-uc.yml

@@ -857,7 +857,6 @@ packages:
 - project: puppet-rabbitmq
   tags:
     stein-py3-uc:
-      source-branch: 1ccddad57e4d53bb3861754a1712b78f3a0fb13f
 - project: puppet-redis
   tags:
     stein-py3-uc:

tags/stein-uc.yml

@@ -860,7 +860,6 @@ packages:
 - project: puppet-rabbitmq
   tags:
     stein-uc:
-      source-branch: 1ccddad57e4d53bb3861754a1712b78f3a0fb13f
 - project: puppet-redis
   tags:
     stein-uc: