remove edx-mktg requirements from GoAgent

docker/build/go-agent/Dockerfile

@@ -31,19 +31,9 @@ RUN apt-get update && apt-get install -y -q \
     libmysqlclient-dev \
     python3-pip
 
-# Install php
-RUN apt-get update && apt-get install -y \
-    php5-common \
-    php5-cli
-
 # Install dependencies needed for Ansible 2.x
 RUN apt-get update && apt-get install -y libffi-dev libssl-dev
 
-# Install drush (drupal shell) for access to Drupal commands/Acquia
-RUN php -r "readfile('http://files.drush.org/drush.phar');" > drush && \
-    chmod +x drush && \
-    sudo mv drush /usr/local/bin
-
 # Install Docker - for Docker container building by a go-agent.
 COPY docker/build/go-agent/files/docker_install.sh /tmp/docker/
 RUN /bin/bash /tmp/docker/docker_install.sh