Lock around LiStartConnection() and LiStopConnection() to fix thread-safety issues. This will hopefully address the crashes seen in 1.0.3 and 1.0.4.

Limelight/Stream/StreamManager.m

@@ -91,20 +91,11 @@
     [opQueue addOperation:_connection];
 }
 
-// This should NEVER be called from within a thread
-// owned by moonlight-common
 - (void) stopStream
 {
     [_connection terminate];
 }
 
-// This should only be called from within a thread
-// owned by moonlight-common
-- (void) stopStreamInternal
-{
-    [_connection terminateInternal];
-}
-
 - (BOOL) launchApp:(HttpManager*)hMan {
     HttpResponse* launchResp = [[HttpResponse alloc] init];
     [hMan executeRequestSynchronously:[HttpRequest requestForResponse:launchResp withUrlRequest: