suppress npm warning by --silent

Dockerfile

@@ -31,7 +31,7 @@ WORKDIR /wechaty
 # https://github.com/giggio/node-chromedriver/issues/70
 COPY package.json .
 RUN  sed -i '/chromedriver/d' package.json \
-  && npm --progress=false install > /dev/null \
+  && npm --silent --progress=false install > /dev/null \
   && rm -fr /tmp/* ~/.npm
 
 # Loading from node_modules Folders: https://nodejs.org/api/modules.html
@@ -39,10 +39,14 @@ RUN  sed -i '/chromedriver/d' package.json \
 COPY . .
 RUN  sed -i '/chromedriver/d' package.json \
   && npm run build \
-  && npm --progress=false link \
+  && npm --silent --progress=false link \
   \
   && mkdir /bot \
-  && (mkdir /node_modules && cd /node_modules && ln -s /wechaty . && npm install @types/node) \
+  \
+  && (   mkdir /node_modules && cd /node_modules \
+      && ln -s /wechaty . \
+      && npm --progress=false install @types/node --silent >/dev/null \
+    ) \
   && ln -s /wechaty/tsconfig.json / \
   \
   && echo 'Linked wechaty to global'