Work on ZonalSummarySpec
Fix TiledPolygonalZonalSummarySpec to work with DataSource changes
Merge pull request #613 from ejc123/ZonalSummaryFix

Add return type annotations to Zonal Summary Methods
Merge pull request #614 from ejc123/FixZonalSummarySpec

Fix TiledPolygonalZonalSummarySpec to work with DataSource changes
Merge branch 'master' of github.com:ejc123/geotrellis

Conflicts:
	src/test/scala/geotrellis/raster/op/zonal/TiledPolygonalZonalSummarySpec.scala
Merge branch 'master' into ZonalSummaryFix