Fix crash on Mavericks caused by using unavailable symbol.

Now using the older dispatch priority queue priority constant instead of the QOS constant. Fixes #2

BuildSettingExtractor/AppDelegate.m

@@ -58,7 +58,9 @@ - (IBAction)handleDroppedFile:(DragFileView *)sender {
                 NSURL *destinationURL = openPanel.URL;
 
                 // Perform the extraction in the background.
-                dispatch_async(dispatch_get_global_queue(QOS_CLASS_USER_INITIATED, 0), ^{
+                // Using DISPATCH_QUEUE_PRIORITY_HIGH which is available on 10.9
+                // Move to QOS_CLASS_USER_INITIATED when 10.10 is the deployment target
+                dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{
                     BuildSettingExtractor *buildSettingExtractor = [[BuildSettingExtractor alloc] init];
                     buildSettingExtractor.includeBuildSettingInfoComments = [[NSUserDefaults standardUserDefaults] boolForKey:TPSIncludeBuildSettingInfoComments];