Added Trove (database) version API tests

Added a new file "test_versions.py" to verify the current
version of the Database API.  Required supporting
functions are added in a new client file "versions_client.py"
under the JSON interface.
Modified api/base.py, etc/tempest.conf.sample, clients.py and
config.py files

Partially implements blueprint: trove-tempest

Change-Id: I3dbe4e40b8b2a1ec3c69573dd40c3c8a643d73d6
Merge "Added Trove (database) version API tests"
Verify more information in floating ip tests

Added checks for:
 - the response from a floating ip creation contains the
   port's fixed ip address;
 - creating a floating ip specifying a fixed ip address;
 - listing all floating ip's from an admin user;
 - non-admin user only sees his floating ip's in a list operation.

partially implement bp: improve-neutron-test-coverage

Change-Id: Ie517a8b51414f9331a8c38822054c6759ac9a01c
Merge "Verify more information in floating ip tests"