Merge pull request #23 from yoonzm/master

UserOffline reason

android/src/main/java/com/syan/agora/AgoraModule.java

                     WritableMap map = Arguments.createMap();
                     map.putString("type", "onUserOffline");
                     map.putInt("uid", uid);
+                    map.putInt("reason", reason);
                     commonEvent(map);
                 }
             });

ios/RCTAgora/RCTAgora.m

     NSMutableDictionary *params = @{}.mutableCopy;
     params[@"type"] = @"onUserOffline";
     params[@"uid"] = [NSNumber numberWithInteger:uid];
+    params[@"reason"] = [NSNumber numberWithInteger:reason];
 
     [self sendEvent:params];
 }