Rename RBD params to controller class

Some time back during crunch time before a release, we discovered
that we needed to add params to the openstack::controller class
in order to make Ceph-backed Glance work correctly.  Due to the lack
of time to get the patch pushed upstream, the patch was applied
locally with the intent of sending it upstream later.  However,
that somehow slipped through the cracks and when upstream later
added the same parameters, they did so using a slightly different
name.  In order to eliminate the local patch, we need to change
core.pp to use upstream's version of the patch.  This commit
does that.

Closes-Bug: #1229176
Merge pull request #181 from CiscoSystems/bugs/1229176

Rename RBD params to controller class