Move --config-dir tests into their own test case

For some reason these were in TemplateSubstitutionTestCase.

Change-Id: Ie2ce1a2a4fd20e5255434c5a5ccf4bc42a5e4beb
Add test cases for default_config_files

It's pretty important we actually test the behaviour of falling back to
a default list of config files. Very surprising that we weren't alrady
testing this.

Change-Id: I903384247480946cc6aed38528695a4b89e717d2
Add CLI vs config file priority test

Add a test to show the current behaviour of config files overriding
CLI values, even where the CLI value comes after the --config-file
argument.

Change-Id: Iaa6dcee49339c096278cc11945cc244a665e6a0a
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 "Move --config-dir tests into their own test case"
Merge "Add test cases for default_config_files"
Merge "Add CLI vs config file priority test"
Merge "Allow Multiple sets of deprecated name/group for options"