Added project for uploading to maven central.
fix links in download page of docs
Add parent class for all map layers that has opacity.

Updated all MapLayer implementations to pass the params to the super classes so that I can apply the opacity to the Geotools style.
Apply opacity to Geotools styles before rendering
add opacity test
change how image is written to disk for debugging
Add a short circuit so that a layer is not processed if opacity == 0.
fix checkstyle violations
Fixed bug with legend output numberOfLegendRows.  It was always at least 1.
fixed java 1.6 compile errors
Merge branch 'development' of github.com:mapfish/mapfish-print into development
don't write debug files.