Now stop discovery when pairing

Limelight/Network/DiscoveryManager.h

@@ -21,6 +21,7 @@
 - (id) initWithHosts:(NSArray*)hosts andCallback:(id<DiscoveryCallback>) callback;
 - (void) startDiscovery;
 - (void) stopDiscovery;
+- (void) stopDiscoveryBlocking;
 - (BOOL) addHostToDiscovery:(Host*)host;
 - (void) removeHostFromDiscovery:(Host*)host;
 - (void) discoverHost:(NSString*)hostAddress withCallback:(void (^)(Host*))callback;

Limelight/Network/DiscoveryManager.m

@@ -69,8 +69,14 @@
     [_mdnsMan stopSearching];
     [_opQueue cancelAllOperations];
 }
+
+- (void) stopDiscoveryBlocking {
+    NSLog(@"Stopping discovery and waiting for workers to stop");
     shouldDiscover = NO;
     [_mdnsMan stopSearching];
+    [_opQueue cancelAllOperations];
+    [_opQueue waitUntilAllOperationsAreFinished];
+    NSLog(@"All discovery workers stopped");
 }
 
 - (BOOL) addHostToDiscovery:(Host *)host {