Fixes Bug 816251 - added rule to ensure signature length doesn't exceed 255

using the transform file system to force signatures to fit in 255 characters.

at the same time, use the new form of transform rules within the processor.
The Transform Rule System was added in Feb of '12 and is based on a generalization of the other rule system systems present in Socorro: collector throttling system and the processor Signature generation rules.  Like that collector system, the TransformRules inspect the arguments passed and dispatch action based on the type.  The input can be functions or classes. Passing a function in is not a failure.  In the latter case, the class must define ```predicate``` and/or ```action``` methods to be accepted in the creation of a transform rule.  The predicate and action functions (or class methods) get combined with the associated args and kwargs to create a new "partial" function.  These partial function become the components of the rule. 

Currently this rule system is being used for the raw crash rewrites (adjusting Product names, version numbers, plugin content URLs, ...). The classifiers (skunk, and support) are also written in term of the TransformRules API.  Transform rules are also key to the functioning of the automatic email sending system.  

Reworking this system is way out of scope for this bug.