pyflakes fixes
replace all `self.assertEqual` with a "regular" assertion
add missing encoding declaration
replace all `self.assertTrue` and `self.assertFalse` as well...
same with `self.assert_` and `self.assertNotEqual`...
and lastly, replace all `self.assertRaises` as well...
use pytest funcargs to set up the database
replace unittest's `setUp` with pytest's `setup_method` (and also introduce a `request` test funcarg)
inline registry tweaks where we don't have access to `config` (in `setup_method`)
follow-up on 010a6ca6, mostly adding the `db_session` funcarg (so that the test can rely on a registry and database to be present)
replace `EventTestBase` with a funcarg (`events`) and finally stop using `UnitTestBase`
Merge remote-tracking branch 'kotti/master' into 'test-setup-cleanups'

Conflicts:
	kotti/tests/test_app.py
	kotti/tests/test_util_views.py
adjust newly added tests to pytest patterns
fix tests related to slots by clearing out registered events
also reset security (i.e. roles) for better test isolation
avoid calling `initialize_sql` when testing app settings

explicitly calling it from tests break the "single connection only" trick, which makes db rollbacks work

please also note, that patching `class TestApp` itself would be nicer, but then pytest cannot match its funcargs anymore... :(
Merge remote-tracking branch 'kotti/master' into 'test-setup-cleanups'

Conflicts:
	kotti/tests/test_util_views.py
re-enable deprecation warnings during test runs and deprecate the "old" unittest base classes

note that ``kotti/testing.py`` needed to be ignored during test collection
prevent deprecation warning from `compiler` module (which is used by pytest itself)
filter deprecation warnings for code that is still tested...