Use Dalli in production and ActiveSupport cache store elsewhere

I had started to add unit tests but was running into errors since app relies on Dalli. Perhaps its preferred that Dalli be installed in all environments? I figured that most people trying this would rather just have something simple like ActiveSupport::Cache::MemoryStore be used for development and test without having to install Dalli locally. I'd like to submit another pull request with some basic unit tests but I wrote them based on not using Dalli locally so I'd have to make some changes.