Add Support for Parameters on Drop Target

[pmichelotti]

Currently the Drop Target rendering does not allow for the production of a parameters child resource under the drop target definition in the edit config. This means there is no way to indicate how resources should be instantiated (ie, what type they should be) when the drop target is used. If you are dragging and dropping components onto a page prior to using the drop target this is not a problem, but if you have baked in the components, using the drop target will not properly instantiate the underlying resource (or at least, it won't do it in the way you probably want it to).

Specifically I am recommending adding a parameters attribute to the DropTarget annotation which takes a list of @Parameter annotations each having a name and value property and an optional namespace property (or we may be able to just reuse the @ContentProperty annotation for this purpose)