Add support for POST services to use req.body and JSON-Schema.

This gets rid of the need to use URL parameters for POST service calls.  All of the dispatch function parameters can be sent in a POST body.  For example:

![poster-inventory-adjustment](https://f.cloud.github.com/assets/571574/1485641/e76ef0e8-4717-11e3-89da-ea08885eb7df.png)