Add Dockerfile for testing/CI

Dockerfile

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+FROM node:8
+
+# Set up the Chrome PPA
+RUN wget -q -O - https://dl-ssl.google.com/linux/linux_signing_key.pub | apt-key add -
+RUN echo "deb [arch=amd64] http://dl.google.com/linux/chrome/deb/ stable main" >> /etc/apt/sources.list.d/google.list
+
+# Update the package list, and install Chrome and unzip
+RUN apt-get update && apt-get install -y google-chrome-stable unzip
+
+# Set up ChromeDriver environment variables
+ENV CHROMEDRIVER_VERSION 2.33
+ENV CHROMEDRIVER_DIR /chromedriver
+
+# Download and install ChromeDriver
+RUN mkdir $CHROMEDRIVER_DIR
+RUN wget -q --continue -P $CHROMEDRIVER_DIR \
+    "http://chromedriver.storage.googleapis.com/$CHROMEDRIVER_VERSION/chromedriver_linux64.zip" && \
+    unzip $CHROMEDRIVER_DIR/chromedriver* -d $CHROMEDRIVER_DIR
+
+# Put ChromeDriver into the PATH
+ENV PATH $CHROMEDRIVER_DIR:$PATH
+
+WORKDIR /app
+
+# see https://git.io/vdao3
+ENV JOBS 1
+
+COPY package.json package-lock.json ./
+RUN npm install
+
+COPY . ./