Converted the api-stubs to coffeescript
Period.Week defined as a number
Route finds one period record by week number as the id
Simulate the server with the Fixture adapter so that it finds periods by weeks instead of ids
Extended DS.Store to add a `findOrInitialize` method
Cleaned up the code
Duplicate what the RestAdapter would return for an error so it works
with the store `findOrInitialize`
Change model to use findOrInitialize to create a model if one does not exist
Week renders with a new period