Change license from GPL 3 to Apache 2.

This commit also updates version numbers and does a bit of cleanup in README.md.
Merge pull request #562 from joshmarcus/topic/change_license

Change license from GPL 3 to Apache 2.
Take a stab at adding Mean
Added Mean to zonal.summary ops
Added Tests for MinDouble and MaxDouble.  I noticed that SumDouble has a test, but these two were missing.
Removed println
Merge pull request #564 from ejc123/master

Mean for raster.op.zonal.summary and 2 missing tests
Need to handle count == 0 case.
Merge pull request #565 from ejc123/FixMean

Need to handle count == 0 case.
Noticed wrong variable comparison when looking over code.
Merge pull request #566 from ejc123/FixMean

Noticed wrong variable comparison when looking over code.
Process path fix for raster layer loading
Merge pull request #568 from lossyrob/fix/loadtileset

Process path fix for raster layer loading
Added SRS transformations to geotrellis.util.srs

-Added two Spatial Reference Systems (SRS), Web Mercator and Lat Long, and the transformations between them.
-Removed geotools dependency from geotrellis-server, the only thing being used for this was the reprojection capabilities of geotools. (Closes #567)

NOTE: Anything using the geotrellis.admin.Reproject object will now need to use the new method.
Remove geotrellis.admin.Reproject
Replaced catalog comment in reference.conf
Added ejc123 to contributors list.
Publish docs and sources in publish task
Merge pull request #570 from lossyrob/publishdocs

Publish docs and sources in publish task
Fix issue #574

Do not ignore item count when calculating median.  Median is
calculated similar to generateStatistics.