include pytest in buildout

otherwise we cannot run tests with development versions of mr.awsome
first test(!)
and another one...
consistently use decorator instead of indivudual context managers
test ``get_devices`` by mocking fabric's ``run`` and ``env``

TODO: there's gotta be a better way...
Cleanup the whole setup.
Add missing file.
Add test stubs, so we see the whole coverage.
Simplify tests.
Remove a few dependencies which are picked up by other packages anyway.
Make tox work with activated virtualenv.
Merge remote-tracking branch 'origin/master' into tests
Use renamed ploy packages.
Merge remote-tracking branch 'origin/master' into tests

Conflicts:
	docs/quickstart.rst
Merge pull request #8 from fschulze/tests

Cleanup and use ploy