Merge pull request #1147 from fmauNeko/docker_smaller_image

Fix npm/yarn cache cleaning

Dockerfile

@@ -29,7 +29,8 @@ RUN BUILD_DEPS=" \
  && npm install -g npm@3 && npm install -g yarn \
  && bundle install --deployment --without test development \
  && yarn \
- && npm cache clean \
+ && yarn cache clean \
+ && npm -g cache clean \
  && apk del $BUILD_DEPS \
  && rm -rf /tmp/* /var/cache/apk/*