fix(ios): expose Ti.Network.HTTPClient#getAllResponseHeaders()

Author: sgtcoolguy

iphone/Classes/TiNetworkHTTPClientProxy.m

@@ -471,6 +471,11 @@ - (void)setRequestHeader:(id)args
 
 #pragma mark - Public getter properties
 
+- (NSString *)getAllResponseHeaders:(id)unused
+{
+  return [self allResponseHeaders];
+}
+
 - (NSString *)allResponseHeaders
 {
   NSDictionary *headers = [[self response] headers];