fix socketio/socket.io-client-swift#25

SwiftIO/SocketIOClient.swift

@@ -335,6 +335,13 @@ public class SocketIOClient: NSObject, SocketEngineClient {
         }
     }
     
+    /**
+    Removes handler(s)
+    */
+    public func off(event:String) {
+            self.handlers = self.handlers.filter {$0.event == event ? false : true}
+    }
+    
     /**
     Adds a handler for an event.
     */