Fix bug in make_updates.py

During the transition in 4f8c792 the gen_host_updates was not update
correctly. Make it a method and call it as we should
Add coverage tox env, do not run flake8 by default

Generate code coverage output during tests
Remove all occurences of servermon package in imports

Removing all of them in imports/documentation/settings etc. It was an
ugly workaround to avoid the problematic nature of django projects pre
1.4 and we can slowly now drop it