Allow user to create locations

Controllers
* Create a locations controller with new and create actions

Views
* Add a location form for generating locations

Models
* Add a location model
* Associate locations with their users

Routes
* Add new and create resources for locations
Ah, gotcha, that makes sense. Still, do you want guest users to be able to create locations? As implemented, if a guest user tried to create a location you'd end up evaluating `current_user.locations`, which will throw an error. I think you want to require login for `create`, at least.