Removes pxebr in clean.sh, updates setup.sh

pxebr bridge is needed by Fuel, but causes issues with Foreman.  It is
now removed in clean.sh.  setup.sh is also updated to be executable and
fixes a bug where grep was being used on output that is in stderr.

JIRA: OCTO-109

Change-Id: I037e168e40f3352a61a604ed6cea21d10250b434
Signed-off-by: Tim Rozet <trozet@redhat.com>
(cherry picked from commit 30361efb7d3bf9525e9d9aadd5c137e9a654d1a4)