Changed how 'Context' was being used.

Context was simply functionality for operations to load layers. I moved the responsibility of owning a context away from the _run function of operations (since the large majority of ops were not using it). Now if an operation needs to load a layer it can return a LayerResult which takes a function that, given a LayerLoader (what was the Context) will give a final result.

Got rid of junit.

Brought in the GeoTrellis object from the server project to Core.

Renamed get -> run and run -> get. This is how it was in the GeoTrellis object, and I think it makes more sense...from a 'run' you get a 'OperationResult' (was CalculationResult), but if you simply call 'get' on the operation or data source you get the bare result (with an exception thrown if there is an error).
Fixed up other projects.
Changed getting tiles by name and Optio[String] store to LayerId case class.

This is in the mix of a project reshuffle.
Separate out admin project, use spray.io
Admin site on spray
Fixed issue with loading tile rasters with extent.

Also made DataSourceLike have a 'get' or 'run', that takes an implicit server parameter, which is imported from geotrellis._ as GeoTrellis.server, which makes running DataSources a snap (see the unit test of this commit for an example).

Fixes #654
Changed admin to use implicit run on DS
Set up the jetty project.
Fixed geotools project
Fixed travis build. Made buildall.sh
Merge pull request #656 from lossyrob/server-spray

Serve the Admin site using Spray, among other things.