Some test cleanups

- align param lists nicely
- get rid of bool_flag (use parametrize instead)
- use pytest.mark.usefixtures for the smtp fixture if the mailbox is not
  actually accessed in the test
- consolidate Room url tests
Delete old/obsolete sqlalchemy tests
Use proper names for RepeatMapping methods
Test RepeatMapping, fix typo
Cleanup parametrizations
Rename argument
Add tests for cancel/reject reservation
Add tests for reservation find_overlapping with
Add stubs for test methods not implemented