Sandlerben

Please review my changes to models and my two new tests. Am I creating relationships in the best way possible? How could I create time exceptions (i.e. on  dates A and B the resource closes early)?
There is probably a way to create helper functions to spit out a bunch of TimeSlots. (Lines 49-55 are identical to lines 33-39, which suggests that they should be factored out into a separate function.)