Handling multi part form upload to the dispatcher.

This change allows the dispatcher to be invoked with a multipart form upload, in addition to a straight GET/POST and form encoded request. The idea is to allow for easier access from web applications that may need to load the request payload from a file form field in the browser. The change falls back to allow a field named "body" to be treated as the request payload. 

This change could also replace the "TestWfsPost" servlet that currently allows for the same functionality.