Merge from vendor branch TNF:

Merge from vendor branch TNF:
Importing databases/ruby-dm-is-state_machine package version 1.2.0.

DataMapper plugin that adds state machine functionality to your models.

== Why is this plugin useful?

Your DataMapper resource might benefit from a state machine if it:

* has different "modes" of operation
* has discrete behaviors
* especially if the behaviors are mutually exclusive

And you want a clean, high-level way of describing these modes / behaviors
and how the resource moves between them.  This plugin allows you to
declaratively describe the states and transitions involved.