Upgrade admin gem to 1.1.6

* Fix asset pipeline in Rails 4
* Upgrade Bootstrap to 3.2
* Upgrade jQuery to 1.11.1
Use a list group for dashboard navigation

* Prevent links from floating in an empty space
Improve legibility to new request form

* Use shorter form fields
* Separate title from content
Merge pull request #14 from alphagov/upgrade-admin-template

Upgrade admin gem to 1.1.6