Use the new build env on Travis

more ram, more cpu, better network

http://docs.travis-ci.com/user/workers/container-based-infrastructure/

more docs coming soon
Merge pull request #511 from joshk/patch-2

Use the new build env on Travis
Tests adjustments:

* Rails 4.2.0.beta4 and Arel 6 are not playing well together right now
* cache bundle in Travis CI
* Factories rearrangement
Force usage of SSL in redirect uris
Allowed SSL URI validations based on the current record. Refactored code to remove obselete nil checks, explicitly stated in initializer that force SSL uri is a code sample.
Changed the behaviour of force_ssl_in_redirect_uri to accept a boolean as configuration.