vcs: remove unused code and test of it Neither git nor mercurial nodes have a _mimetype attribute. Only test_nodes.test_mimetype monkey patches it and that to me seems just wrong. Thus, remove that part and fix the test with some usefull assertions. Found by pylint.

babel >= 0.9.6, < 2.4
waitress >= 0.8.8, < 1.0
pytest ~= 3.0
pytest-runner
pytest-sugar>=0.7.0
pytest-catchlog
pytest-localserver
mock
sphinx
webtest < 3