Koji Arai

Fix vulnerable dependencies

If uploaded image height is smaller than 200px, it is extended too much.

see #773

``` $ docker --version Docker version 17.12.0-ce, build c97c6d6 ``` `docker build . ` is failed at https://hub.docker.com/r/sdelements/lets-chat/builds/bjqta6msdmqrevvmzyuor3m/ I fixed some problem in Dockerfile * `npm cache clean` needs `--force`...