Feature Request: use OWS Context (an "external" WPS process description)

# Description

The [OGC OWS Context](http://www.owscontext.org/) can be used to describe a WPS process. The WPS process description would then be independent of the WPS service implementation. A processing tool could be bundled with its WPS process description (OWS Context document) and picked up by a any WPS service which is able to read OWS Context documents. Processes would become plugins with a plugin description which can be used by different WPS serivces without changes.

# Steps to Reproduce

# Additional Information

* [Earth Observation (EO) Cloud Processing Hackathon](http://www.opengeospatial.org/projects/initiatives/eocloudhack) using an "Application Package"
* [OGC Testbed-13 Application Package](http://docs.opengeospatial.org/per/17-023.html) using OWS Context