Work on ZonalSummarySpec
Change ZonalMin, ZonalMax, ZonalMean to return Int
Merge branch 'master' of github.com:ejc123/geotrellis

Conflicts:
	src/test/scala/geotrellis/raster/op/zonal/TiledPolygonalZonalSummarySpec.scala
Merge branch 'master' into ZonalSummaryFix
Change ZonalMean to return Double
  Make one Mean case class for ZonalMean and ZonalMeanDouble
  Silence success cases in TiledPolygonalZonalSummarySpec
Merge pull request #619 from ejc123/ZonalSummaryFix

Change zonal {min,max,mean} to Int instead of Long