Creates user-bar many to many relationship through bar_gig_memberships

* Creates owner-owned bar relationship
* Generates bar_gig_membership model
* Adjusts partials to display new associations
I'd like to keep it because I'm going to try testing soon and there are a number of other such test files for my other models that would be painful to recreate...what do you think?  In my defense, you let me keep they others....