Fixing rvm and ruby and gem and bundle for marketing goagent

docker/build/go-agent-marketing/Dockerfile

@@ -2,8 +2,8 @@ FROM edxops/go-agent:latest
 
 # Install necessary modules for running make requirements in edx-mktg
 # Using rvm so we can control the ruby version installed. This also installs gem 2.6.12
-RUN bash -c 'apt-add-repository -y ppa:rael-gc/rvm && apt-get update && \
-    apt-get install -y rvm && source /usr/share/rvm/scripts/rvm && \
+RUN bash -c '\curl -sSL https://get.rvm.io | bash -s -- --ignore-dotfiles && \
+    usermod -aG rvm go && source /etc/profile.d/rvm.sh && \
     rvm install ruby-2.4.1 && gem install bundler -v 1.16.0'
 
 # Installs node 8.9.3 and npm 5.5.1 as of 12/13/17. Unlikely to change much since node 9 is a stable version for other OS