Fix user group for Ruby

This fixes ruby template to set app group properly. Fixes
[openfaas#41](openfaas#41). Before
used to add GEO data for user, after the change adds group to user

Signed-off-by: Ivana Yovcheva (VMware) <[email protected]>

Author: ivanayov

template/ruby/Dockerfile

@@ -23,7 +23,7 @@ WORKDIR /home/app/function
 RUN bundle install 
 
 RUN addgroup -S app \
-  && adduser -S -g app app
+  && adduser app -S -G app
 
 RUN chown app:app -R /home/app