added features to deleteDistResource service call.

1) Overloaded the method, providing a version that accepts a HasPaths
object.
2) Refactored the original version so that it passes through to the new
version.
3) Changed the callback of the original method so a HasPaths object is
returned.
4) Created encode class method for DiskResourceServiceFacadeImpl to
encapsulate the JSON autobean encoding code.
Merge branch 'master' of https://github.com/iPlantCollaborativeOpenSource/ui-commons-module