Add pundit for user roles

[jacobherrington]

Refs #65 ( and #66 )

User roles still need to be assigned manually, but the models exist to assign them. Any role can be added in seeds.rb and then assigned in the console.

[mobjohnson]

Thanks for contributing!!!

Can you add tests that show the functionality, using existing User and Organization instances? This is not just to test it, but to show other coders how this should be used. Something like an Org Admin can do this. A non-Org admin can not do that. Same for the Charter Admin. Not every use case, but more than what you presently have.

Make sure you use existing User and Organization instances, or the Google Maps API will be mean to you!!!

[jacobherrington]

@mobjohnson I added some tests for the models. This PR doesn't actually implement any Pundit policies (except those generated in ApplicationPolicy.rb but those aren't being used atm), it just sets up the infrastructure to do so. Specifically fulfilling #65 and #66, but not the issues depending on them. I'm happy to work those too, but I think they should come after this PR so that anyone familiar with Pundit can also contribute.

[mobjohnson]

@jacobherrington Thanks for adding some more tests, and agree further testing would be in another story.