Update govuk_admin_template to 1.1.2

* Update jQuery to 1.11.1
* Update Bootstrap to 3.2
* Also update from formtastic rc3 to release version
Use gem's input class helpers

* Remove old `form-md` classes no longer needed
Merge pull request #115 from alphagov/update-admin-gem

Update govuk_admin_template to 1.1.2