GEOMESA-311 Handle 'attr1 and attr2' filters

If multiple attribute filters are indexable, use the first one
In the future, a query optimizer will make more informed decision
I like this function; I'm trying to figure out if 'partition' or 'find' could work as well.  (Or in general, if there's something else which would be more atomic in the scala collections.  I'd suggest reading through http://www.scala-lang.org/api/current/index.html#scala.collection.Iterable once to see if you find anything useful.)