51925771 Remove the log_events table and LogEvent model.
51925771 Removed obsolete model, fixed associated behave tests.
Merge branch 'develop' into feature/remove-log-event-model

Conflicts:
	src/service_specs/steps/ggrc_http.py
Merge pull request #135 from reciprocity/feature/remove-log-event-model

51925771 Remove obsolete table and model, update related tests.