This is my organization (RESTful)

The This-is-my-organization feature is a way for a user to request admin status for a charity. A "This is my organization button"  shows on each organization's page. When a logged in user clicks the button, the user's status is changed to reflect the pending organization.

The site administrator can see users awaiting approval on the users index page and approve the pending users as charity admins.

Still to be implemented: 
* This is my organization button does not show for users who have requested admin status for the org.
* Site admin receives email notification of pending users.

Staged at `http://whispering-springs-4368.herokuapp.com/'

Many thanks to Jon and Marcelo for pairing on this feature.