Add a script to run unit tests within auth_lti package.  Add a tests package with a few tests of the custom role key merge that is being added as part of this feature branch.  Filter out any empty roles from the merged list.  Update requirements in setup.py to remove unused django-filter and to include mock as a test requirement.  Remove *.html from MANIFEST as there are currently no html files.  Add .egg to gitignore.

Make corresponding mixin for LTI roles being required.  Remove GroupRequiredMixin and LoginRequiredMixin since the former is not used in LTI requests and neither was being used currently anyway.  Require django_braces with this library and use it's LoginRequiredMixin instead.  Update version.