Add some more documentation about default values for attributes in Model.
Merge branch 'master' of https://github.com/gregjacobs/Data.js
[Ajax Proxy] Don't add the `id` property if the Model's ID is null.
Add static load() method to Model.
A couple of doc fixes.
Add properties to Model and Collection classes to be able to identify them as such without an instanceof check.

This is to allow the circular dependencies to be removed from the library.
Remove circular dependencies from ModelAttribute and CollectionAttribute classes, which brought in the Model and Collection classes simply in order to run instanceof and Class.isSubclassOf() checks.
Add properties to DataComponent class to be able to identify it as such without an instanceof check.

This is to allow the circular dependencies to be removed from the library.
Remove circular dependencies from the NativeObjectConverter, which brought in the Model and Collection classes simply to run instanceof checks.

Also clean up the NativeObjectConverter's unit tests a bit.
Remove final circular dependencies from Model and Collection classes.
Latest build files for 0.7.1, which removes circular dependencies from the library.
Merge branch 'master' into model-clear-method

Conflicts:
	src/Model.js