Removed unused pending configuration work
Changed Version in the element as well as the schema, from string to SemanticVersion.

Explicit implementations of element interfaces so that the internal implementation is easier to work with in the internal behavior.
Added proper fixtures for all schema classes.
Added validation to the schema models.
Added default name property to component schema, which in combination with CanRename allows for fixed-name component "properties" (i.e. associations).
Fixed usage of strings for $Items instead of the corresponding constant.
Added missing unit tests for collection and component implementations.
Added schema property to IProperty, which will determine the property behavior.