remove cron pkg (#1084)

Dockerfile

@@ -10,7 +10,7 @@ SHELL ["/bin/bash", "-c"]
 RUN groupadd -g $userid -r gi-bill-data-service && \
     useradd -u $userid -r -g gi-bill-data-service -d /srv/gi-bill-data-service gi-bill-data-service
 RUN apt-get update -qq && apt-get install -y \
-    build-essential git curl wget libpq-dev dumb-init shared-mime-info nodejs cron
+    build-essential git curl wget libpq-dev dumb-init shared-mime-info nodejs
 
 RUN mkdir -p /srv/gi-bill-data-service/src && \
     chown -R gi-bill-data-service:gi-bill-data-service /srv/gi-bill-data-service