fix for rel-eng sysrepo issues

the sysrepos have an update postgres-devel rpm that
is not in the metadata. Ticket in, but this workaround
should fix

Change-Id: Id0a43430489d9d10daf9cc96ad3751481b5b328a
remove tempest config from basic settings

There are tempest settings in default and can be overriden
in the job_settings.yml. Not needed here

Change-Id: Ief1bd79d6d30ee49d3fb95f22e412eb625f1e899
ps, remove unneeded workaround

remove installa additional rpms
remove rhel repo settings from settings file

Change-Id: Ie557edd1e348803b305239625ca285e613e7d6aa
python module testtools is now required for tempest

Change-Id: I4c898aabe0359ca1c0772110fe057b619b0c2564
epel: use mirror list

Change-Id: I2687057d3189d1092a5c734635a6c598266aa85a
Only add optional repo manually when distro != 7.0

Also, add EPEL beta for RHEL 7

Change-Id: Ibefe7ece5f318987c05e17506170b2677742de2b