The horizon settings have changed and the corresponding changes
were not picked up the trove-dashboard. Import the horizon settings
file to prevent code skew and add the panels to the list of
installed apps.
Once the above was fixed it revealed one code change that was
needed due to commit ea0e472edd194243392fd51a5af3a3a77101fddd.
The Paginated object was changed in the above commit resulting
in the change in the trove.py file. Also changed the test to
reflect the new signature.
Also changed the tox.ini to be consistent with the horizon tox.ini.
Change-Id: Id484fe373b79f00b90ca8b890aa3b9f73a475a50
59525185d5