Merge pull request #2822 from benzguo/method-override-warning

Fix "method override not found" warnings on Xcode 7b2

AFNetworking/AFNetworkReachabilityManager.m

@@ -155,6 +155,11 @@ static void AFNetworkReachabilityReleaseCallback(const void *info) {
     return self;
 }
 
+- (instancetype)init NS_UNAVAILABLE
+{
+    return nil;
+}
+
 - (void)dealloc {
     [self stopMonitoring];
 

AFNetworking/AFURLConnectionOperation.m

@@ -204,6 +204,11 @@ static inline BOOL AFStateTransitionIsValid(AFOperationState fromState, AFOperat
     return self;
 }
 
+- (instancetype)init NS_UNAVAILABLE
+{
+    return nil;
+}
+
 - (void)dealloc {
     if (_outputStream) {
         [_outputStream close];