Re-enable nova services

When grizzly-hack.yaml went away in I706ea95e, nova services
stopped being enabled by default (apparently they weren't
mapped individually elsewhere).  We shouldn't need to force
the end user to map enablement for these individually, so this
patch adds enablement via common.yaml (the next point up in the
hierarchy from where grizzly-hack.yaml used to sit, so it's
low enough to be overridden by anything that used to override
those parameters anyway).  This is done by a single parameter
with a corresponding data mapping in data_mappings/common.yaml.

Change-Id: Ib658e53d4f6d67337abf42a6ed18cd6e6dd40cda
Merge "Re-enable nova services"