GEOMESA-234 using lexicoders for secondary index values

* Using mango lexicoders for primitive types
* Moving some encoding/decoding logic into more consistent locations
* Updating attribute strategies for querying with lexicoders
Ok, I was confused by this refactoring, but I am now convinced that nothing went wrong.  

As a general discussion, I'm a reading it right that an Id query would be an Density query?  That sense does not make.