Java Bindings

I've created initial Java bindings for the current STIX schema. Please note that I was required to make one relatively small change to the STIX-Common schema. This was unavoidable. Please review the commits and comments for details. While not required, I recommend that you make a change to the STIX-Indicator schema. There is a complex type, IndicatorType, that has a child element IndicatorType. This seems like a bad idea.