Allow Multiple sets of deprecated name/group for options

We currently allow just one name/group for deprecation. For adoption
of oslo db by multiple projects, we need to be able to specify
multiple sets of deprecated name/group.

For example connection is defined as follows in various
projects and we need to be able specify all the combinations
for being able to upgrade from Grizzly to Havana

Nova: Section - DEFAULT; Key - sql_connection
Cinder: Section - DEFAULT; Key - sql_connection
Glance: Section - DEFAULT; Key - sql_connection
Quantum: Section - DATABASE; key - sql_connection
Keystone: Section - SQL; key - connection

Please see discussion on the dev mailing list and on the
review - https://review.openstack.org/#/c/27345 for
oslo-incubator

Change-Id: I8c2097275242a4fdbd4f0f9fb4e293d1ba793d16
Merge "Allow Multiple sets of deprecated name/group for options"