Update puppet-ceilometer to latest master

Changes include:
 - Add support for configuring coordination/backend_url
 - Clean up stray copy-paste error
 - Release 5.0.0 - Juno

Hash references:
 - old commit: 1d78470e5023e2ca6adef47c904d14d046dd87d1
 - new commit: 64d872cdef84867728087609996e5d9993398416