Minor tweaks in README

[duglin]

postgres should be gitlab-postgres in postgres.yaml since the build cmd tags it as gitlab-postgres

docker.io should be registry.ng.bluemix.net in postgres.yaml and gitlab.yaml - why have them do the substitution on that part of the image names?

To fix it run:

sed -i "s/postgres:latest/gitlab-postgres:latest/" postgres.yaml
sed -i "s/docker.io/registry.ng.bluemix.net/" postgres.yaml 
sed -i "s/docker.io/registry.ng.bluemix.net/" gitlab.yaml

[Tomcli]

We updated our README and yaml files based on some of your suggestions. Thank you very much for your suggestions.