Handle search misspellings

To make this slightly less messy, we could offload the Similarity search to the controller. 

In this way, Search.search could go back to serving simple ActiveRecord::Association's. At the same time, the SearchController would do a first search, check the returned array, directly ask for similarities to Search::Similarity, and use the result to issue a second Search.search. 

Just a matter of taste, I guess. :confused: