Installs bundler 1.5.1 on travis
Installs bundler 1.5.1 on travis

Bundler 1.5.0 has issues with minitest on Ruby 2.1
tomdale/ember-appkit-rails,DavyJonesLocker/ember-appkit-rails,tomdale/ember-appkit-rails,DavyJonesLocker/ember-appkit-rails