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
Wow, never seen condOpt.  I think this might be more clear (sadly, more verbose)
```
if(indexed) Some(new AttributeIdxLikeStrategy) else None
```
(Does our style allow that to be one-lined?)