New GM Pipe Organ Instrument

A response to this post on the forum: http://musescore.org/en/node/27106
a simple GM Pipe organ has been added to instruments.xml and the old Pipe Organ which controlled Aeolus has been renamed to Aeolus Organ. This is part of the preparations required for the removal of Aeolus should we fail to resolve issues with Fons Adrianssen.