for comments - GEOMESA-233 adding scalding job to index attributes through geoserver UI

Still TODO - 
* create ticket for the TODO in the code
* error handling in UI for failed m/r jobs
* unit tests

scala> val m = new java.util.HashMap[Any,Any]()
m: java.util.HashMap[Any,Any] = {}

scala> m.get(1)
res1: Any = null

scala> m.get(1).asInstanceOf[String]
res2: String = null