Added rasterization operations
Merged in upstream changes.
Added AsTiledRaster operation and Rasterization operations.
Made the TileSetRasterData take a server.
Fixing benchmark project.
Merge pull request #448 from lossyrob/ops/rasterization

Rasterization Operations, AsTiledRaster operation
Merge branch 'master' of github.com:geotrellis/geotrellis into 0.8.1
Increment release candidate to RC2.