Don't try to close server sockets twice.

This may have been the cause of bug #69. Removed the wait-for-shutdown
code in DroidtoothPlugin that was added to attempt to avoid that bug.

briar-desktop/src/org/briarproject/plugins/bluetooth/BluetoothPlugin.java

@@ -157,7 +157,6 @@ class BluetoothPlugin implements DuplexPlugin {
 			} catch(IOException e) {
 				// This is expected when the socket is closed
 				if(LOG.isLoggable(INFO)) LOG.info(e.toString());
-				tryToClose(ss);
 				return;
 			}
 			callback.incomingConnectionCreated(wrapSocket(s));