Upgrade Bootstrap to 3.3

http://blog.getbootstrap.com/2014/10/29/bootstrap-3-3-0-released/
Upgrade Jasmine to 2.1

https://github.com/jasmine/jasmine-gem/releases/tag/v2.1.0
https://github.com/jasmine/jasmine/blob/master/release_notes/2.1.0.md
Upgrade Capybara to 2.4.4
Merge pull request #53 from alphagov/upgrade-bootstrap

Upgrade Bootstrap to 3.3