feat(DirtyModel): Adds $restore method

closes #31
feat: adds the $single method to Model and singleton method to $restmod

* The singleton service is a shorcut to create a single resource with a given object definition.
* The $single method allows to create Model instances bound to a given url.

Closes #29
refactor: changes plugins test file names
feat(Builder): adds ability to define class methods and hooks in the object definition using special prefixes.

* A '@' prefix defines a new class method/property.
* A '~' prefix defines a hook.

Closes #32
bumps v0.10.2