635 reservation model

* Move scopes into a module
* Merge in ReservationsBase module 
* Simplify scopes via chaining
Not to be nitpicky, but if we're trying to follow style guides we should make sure all of our curly braces and commas have the appropriate white space next to them (I noticed a few missing spaces in this file while reviewing all the scopes). I know that it's trivial but I think we should stick to it for all new code.