Upgrade capybara  to 2 1

Upgrading capybara to 2.1 and running the specs, I've noticed that it only had one problem. Capybara deprecated the method wait_until, as explained here: http://www.elabs.se/blog/53-why-wait_until-was-removed-from-capybara

Evergreen only used that method in one place, and, as far as I know, it was only to prevent the evergreen tests to hang forever. So, I moved the timout helper ( that wait_until used ) to evergreen and used it in replace of wait_until.

Specs are passing, so it seems ok.

Can you review this please?

Thanks.