Create admin section:

- https://www.pivotaltracker.com/story/show/67751518
[Finished #67751518]
Updates based on PR comments
- #10
- https://www.pivotaltracker.com/story/show/67751518
[Fixes #67751518]
Merge pull request #10 from joshclick/admin_section

Create admin section:
Sign in as another user from admin

- https://www.pivotaltracker.com/story/show/67918148
[Finishes #67918148]