Add new test and clean targets to Makefile
Add new test and clean targets to Makefile

Test targets were added to run py.test and tox with the test instance
variable set to review.openstack.org, so that online tests can be run

   make test-online quickly runs py.test
   make test-all-online runs tox including online checks

Expanded the range of clean targets to include make clean-dist,
which removes all the tox virtual environments and any .egg files
found in the tree.

make targets clean and clean-pyc now also remove all __pycache__
directories. make clean and clean-build clean out the docs and coverage
output files.

kdopen/gerritssh,kdopen/gerritssh