Refactored bed verification

* Added clarity_process_io role
* Added clarity_bed class
* Added clarity_plate class

Tried to make bed verification a lot simpler, and a lot
quicker (requests are batched now).
Updated the POD a bit more
Modified structure of bed verification config
Fixed a test
Added clarity udf parent class

Parent class used as a simple wrapper for a udf XML::Element.
Adds simple helper methods get_name and get_value
Merge pull request #201 from jbeast/bed_verification_refactor

Bed verification refactor