Tests uses settings.py for a correct execution.
Muranodashboard settings file is not supported
and used be copied from the corresponding version of horizon.
This patch prevent tests from future failing.
Horizon settings file now will be used and
no problem with requirements should arise.
Since settings.py is not used in tests anymore, it can be deleted.
Change-Id: Ibb1101c4859db678b3678456991e446784afc1d1