Extensions for creating QRDA documents

Not sure if you'd be interested, but this branch represents work we did to include needed QRDA structures into the CCDA xsd. With these extensions, we've been able to create valid QRDA Category I and Category III documents for Meaningful Use Stage 2. The changes are fairly minor and would not break any existing code that relies on CCDA because these are extensions, not changes, to the current structure. These extensions can simply not be used. The most common extension is the attribute named "valueSet" which becomes part of the CD family of data types.

ex.
CD cd = new CD();
cd.setCode("thecode");
cd.setCodeSystem("code system");
...
cd.setValueSet("1.1.1.1.1.1");