if there exists one and only one of the camera or shutter or focus stage device, automatically assign that device to the system role.
if there exists one and only one of the camera or shutter or focus stage device, automatically assign that device to the system role.

git-svn-id: 03a8048b5ee8463be5048a3801110fb50f378627@7141 d0ab736e-dc22-4aeb-8dc9-08def0aa14fd

kmdouglass/Micro-Manager,kmdouglass/Micro-Manager