Add a check for a custom role key - specified via an optional project parameter - and merge into the existing list of roles if present.
Add info on custom role key to README doc.
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.
Remove apparently unneeded INSTALLED_APPS setting, as well as the LTI_CUSTOM_ROLE_KEY setting.  Update middleware to use hasattr instead of getattr.  Update tests to set the LTI_CUSTOM_ROLE_KEY django setting with a context manager block in each required test.
Merge pull request #5 from Harvard-University-iCommons/feature/merge_custom_roles

Add a check for a custom role key - specified via an optional project pa...