Only dispatch_async on limelight-common's threads

Limelight/Stream/StreamManager.m

@@ -79,11 +79,20 @@
     [opQueue addOperation:_connection];
 }
 
+// This should NEVER be called from within a thread
+// owned by limelight-common
 - (void) stopStream
 {
     [_connection terminate];
 }
 
+// This should only be called from within a thread
+// owned by limelight-common
+- (void) stopStreamInternal
+{
+    [_connection terminateInternal];
+}
+
 - (BOOL) launchApp:(HttpManager*)hMan {
     NSData* launchResp = [hMan executeRequestSynchronously:
                           [hMan newLaunchRequest:_config.appID