Specify group os-apply-config for config resources

This will indicate to os-collect-config that this config
resource represents os-apply-config configuration data,
so it can only write out top-level config files for
os-apply-config data (or Heat::Ungrouped for backwards
compatibility).

Change-Id: I3552fdd6df8106ab83cfd17d5f4b137cf33fbc36
Related-Bug: #1299109
Merge "Specify group os-apply-config for config resources"