v1.4.0. Improvement.

v1.4.0 April 18, 2013
	- By default when over-writing a model attribute with a new model, we
will replace the old model with the new model, rather than copying in
the attributes of the new model into the old model
		- This can be turned off by using `replaceModel: false` inside your
set options
	- Added `isPreparedValue(key,value)` method