Delete python bytecode before every test run
Delete python bytecode before every test run

Because python creates pyc|pyo files and __pycache__
directories during tox runs, certain changes in the tree,
like deletes of files, or switching branches, can create
spurious errors.

The target bytecodes for deletion are in normal directories,
but not in dot started directory.

Change-Id: If79295af6c15da04017787daccfb67a9817ac27c
Fixes: bug #1532525

openstack/searchlight,openstack/searchlight,openstack/searchlight