mw/tools/scap now uses tox entry points

Got rid of pep8/pyflakes jobs in favor of tox entry points to envs py27
and flake8.  Drawback: they are only in the 'test' pipeline, hence
untrusted users will have no test run for now.

Change-Id: I4e2ec523b5e6f924fef9c495182d06586ba3bfa6