Installs Active Admin
Merge branch 'override-registrations-controller' into add-activeadmin
ActiveAdmin setup needs routing changes from this branch

Conflicts:
	config/routes.rb
User model needs to be registerable for sign_up to work
Adds a users show page at /dashboard. Fixes #14.
Merge branch 'master' into create-users-show-page
Removed line that was duplicated from merging
Merge pull request #26 from WGBH/create-users-show-page

Create users show page