Add git to Dockerfile (#1426)

Signed-off-by: Matthew Peveler <matt.peveler@gmail.com>

Dockerfile

@@ -13,10 +13,11 @@ COPY Gemfile.lock .
 RUN apt-get update \
     && apt-get install -y --no-install-recommends \
         build-essential \
+        git \
         nodejs \
     && gem install bundler \
     && bundle install \
-    && apt-get remove -y build-essential \
+    && apt-get remove -y build-essential git \
     && apt-get autoremove -y \
     && rm -rf /var/lib/apt/lists/*