Have better docker caching (#63)

Dockerfile

@@ -4,11 +4,14 @@ RUN apk add --no-cache tini
 
 WORKDIR /RTL
 
-COPY . /RTL
+COPY package.json /RTL/package.json
+COPY package-lock.json /RTL/package-lock.json
 
 # Install dependencies
 RUN npm install
 
+COPY . /RTL
+
 EXPOSE 3000
 
 ENTRYPOINT ["/sbin/tini", "-g", "--"]

Dockerfile.arm32v7

@@ -11,9 +11,14 @@ WORKDIR /RTL
 
 COPY . /RTL
 
+COPY package.json /RTL/package.json
+COPY package-lock.json /RTL/package-lock.json
+
 # Install dependencies
 RUN npm install
 
+COPY . /RTL
+
 FROM arm32v7/node:10-jessie-slim
 
 WORKDIR /RTL