Remove the explicit dependency on sass-rails. Fixes #891
Use engine cart ~> 0.1.3 for testing
Reduce number of builds
Remove the facet parameter if it's empty
The search session gets serialized as a Hash not a HWIA. See e50c671
Merge pull request #892 from projectblacklight/fix-rake-task-require

Get the 4.7 branch working on Rails 4.1 and Ruby 2.1.1