Enable tests modules to auto-import all test files in their directories.
updating error logic in coach reports; adding tests to verify if-then-else logic.
better documentation and code structure, based on self-code review
cleaning missing topics.  Hard problem
fixing bug in looping over children, recovered one missing child.
Merge branch 'coach_reports_error_message' into empty_subtopics_1
add tests for checking that knowledge map elements are on the page (though does not confirm that they are visible.
wrap all API calls with error catching, so all API return Json-based errors
update video_download
Merge remote-tracking branch 'upstream/develop' into empty_subtopics_1
fixing up error messages.
raise Http404, not return
Merge branch 'develop' of github.com:learningequality/ka-lite into safe_api_errors

Conflicts:
	kalite/securesync/api_views.py
updating formatting on video_download
Merge pull request #437 from bcipolli/coach_reports_error_message

Coach reports error message
Merge branch 'release-0.10' of github.com:learningequality/ka-lite into testing_testing

Conflicts:
	kalite/central/tests/__init__.py
	kalite/main/tests/__init__.py
	kalite/securesync/tests/__init__.py
Added a helper function for importing * from all modules in a directory.
Tweaks to auto-import function.
Tweak to docstring for import_all_from function.
Removed "exclude_special_modules" param from "import_all_from".