Travis: Remove JRuby, Rubinius, and 1.9.3

* Adds Bundler caching
Merge pull request #32 from dockyard/doug-fix-travis

Travis: Remove JRuby, Rubinius, and 1.9.3
Update Capybara to v2.2.0
Merge pull request #33 from dockyard/doug-update-capybara

Update Capybara to v2.2.0
Version bump
Adds methods for retrieving headers from a message and updates README.

Adds CHANGELOG.
Merge pull request #36 from dockyard/md-retrieve_headers

Adds methods for retrieving headers from a message.
Correct inspect
Merge pull request #37 from dockyard/bc-correct-inspect

Correct inspect
Removed file
Delegation
Delegation
Version bump
Make changes to spec_helper.rb more prominent

This took me 15 minutes to find. Hope the next developer won't.
Merge pull request #39 from hasclass/patch-1

Make changes to spec_helper.rb more prominent