Implement sponsor feature and add adiitonal scenarios for earlier features

Part of PT story https://www.pivotaltracker.com/story/show/76232594

- add more tests to admin users feature
- add additional scenario to partner featue
- added sponsor feature 
- fix delete links being show for sponsors by active admin
- added linked name to sponsor index view
- refactored authenticated user step into background
Is the cancellation functionality explicitly implemented by the app? Otherwise, isn't this testing something that doesn't need to be tested - browser's handling of JavaScript and sending requests?