Organizations CRUD

Adds organizations crud operations according to the user story from PT:
https://www.pivotaltracker.com/story/show/77974308

Accessible on Heroku instance: 
http://sleepy-reef-7794.herokuapp.com/admin/organizations

Implements organizations crud with cucumber tests (similar to the ones for partners) and rspec tests for the model. 
My intention behind writing similar tests on other models was to test the initializer methods: ensure that they set defaults, but do not override existing values. (Admittedly, this is redundant with the spec for the Initializer module.) This is what your status tests accomplish here. To follow the same logic, the test on L48 ought to be paired with another, testing that when valid `start_time` is provided in the call to `Organization.new`, it is not overridden by the initializer's `default_start_date_to_today` method.

By contrast, the tests on L43 & L53 merely test Ruby's `attr_accessor`, which is definitely unnecessary.