Fix locales not being reset properly in tests.

There's an oversight in `SitesIntegrationTest` that changes the locale without resetting it properly afterwards. This meant that if the tests were executed in a certain order, string comparisons in tests later on would fail. 

See [this failed travis build](https://travis-ci.org/comfy/comfortable-mexican-sofa/jobs/29735616) for an example. Run `rake test:all TESTOPTS=" --seed 8283"` for a local example.

This PR adds a method `reset_locale` method to `SitesIntegrationTest` that resets the locale after each test as necessary.

It also includes the commit in @sepastian's PR #490 in order to produce a clean test run.