This patch also adds checks for executable files in
pep8 job.
nose ignores executable files by default, so it is important
to ensure executable flag is not set for test files [1].
openstack_dashboard/test/test_plugins/panel_tests.py was not
tested actually and it was broken. This commit fixes it too.
[1] http://nose.readthedocs.io/en/latest/usage.html#cmdoption-exe
Co-Authored-By: Ivan Kolodyazhny <e0ne@e0ne.info>
Change-Id: I3a124fa2f9f0676b2b43a094e32e3d8b18fa6005