GEOMESA-173 Extract avro features into its own subproject

Moved AvroSimpleFeature into its own subproject.  Implemented
AvroSimpleFeatureFactory to create avro simplefeatures when
using SimpleFeatureBuilder
Perhaps the AvroSimpleFeature.apply(sf: SimpleFeature) should use this block of code as well to have a single block that creates features. The builder is more heavy-weight than the apply method though.