Dockerfile: cleanup and add en_US.UTF-8 locale

Closes #84
Closes #83

Thanks @xMrWhite, @frol and @sr229.

.github/CODEOWNERS

-* @coderasher @kylecarbs
\ No newline at end of file
+* @coderasher @kylecarbs
+Dockerfile @nhooyr

Dockerfile

 FROM node:8.15.0
 
 # Install VS Code's deps. These are the only two it seems we need.
-RUN apt-get update
-RUN apt-get install -y libxkbfile-dev libsecret-1-dev
+RUN apt-get update && apt-get install -y \
+	libxkbfile-dev \
+	libsecret-1-dev
 
 # Ensure latest yarn.
-RUN npm install -g yarn
+RUN npm install -g yarn@1.13
 
-# In the future, we can use https://github.com/yarnpkg/rfcs/pull/53 to make it use the node_modules
-# directly which should be faster.
 WORKDIR /src
 COPY . .
-RUN yarn
-RUN yarn task build:server:binary
+
+# In the future, we can use https://github.com/yarnpkg/rfcs/pull/53 to make yarn use the node_modules
+# directly which should be fast as it is slow because it populates its own cache every time.
+RUN yarn && yarn task build:server:binary
 
 # We deploy with ubuntu so that devs have a familiar environemnt.
 FROM ubuntu:18.10
-RUN apt-get update
-RUN apt-get install -y openssl
-RUN apt-get install -y net-tools
 WORKDIR /root/project
 COPY --from=0 /src/packages/server/cli-linux /usr/local/bin/code-server
 EXPOSE 8443
+RUN apt-get update && apt-get install -y \
+	openssl \
+	net-tools
+RUN apt-get install -y locales && \
+	locale-gen en_US.UTF-8
+# We unfortunately cannot use update-locale because docker will not use the env variables
+# configured in /etc/default/locale so we need to set it manually.
+ENV LANG=en_US.UTF-8
 # Unfortunately `.` does not work with code-server.
 CMD code-server $PWD