Use the new build env on Travis

http://docs.travis-ci.com/user/workers/container-based-infrastructure/
Merge pull request #53 from joshk/patch-1

Use the new build env on Travis
[JRO] the Forwardable module + Rails 4.2. No good

From: https://github.com/cequel/cequel/issues/193

> So it sounds like ActiveSupport 4.2 introduces an incompatible
> definition of instance_delegate that clobbers the same method as defined
> in Forwardable; is that correct? If so, this seems like a regression in
> ActiveSupport—Forwardable is, after all, part of the standard library,
> so Rails shouldn't make it impossible to use it.

Subclassing Module and using the delegate class method will effectively
get around this.
[JRO] Add rails 4.2 to .travis.yml