refresh dockerfile (it's smoller and faster now!)

Dockerfile

@@ -1,18 +1,13 @@
 FROM node:10 AS builder
-# ENV NODE_ENV production
-COPY ./UI /src/UI
-RUN cd /src/UI && yarn && yarn build
-
-COPY ./Server /src/Server
-RUN cd /src/Server && yarn
-
-RUN cp -r /src/UI/build /src/Server/public
-
+WORKDIR /src
+COPY . /src
+# we double yarn here to strip off dev-only packages that are needed at build time.
+RUN yarn --frozen-lockfile &&\
+    yarn build &&\
+    yarn --prod --frozen-lockfile
 
 FROM mhart/alpine-node:10
 ENV NODE_ENV production
 WORKDIR /dist
-EXPOSE 6769
-RUN npm i -g pm2
-COPY --from=builder /src/Server /dist
-CMD pm2-docker index.js
+COPY --from=builder /src /dist
+CMD node index.js