Updating era-test to be a proper staging environment

[weiweishi]

This is to make ERA-test a proper staging environment

• use RAILS_ENV=staging instead of test
• Add staging environment in Hydranorth (copy production.rb into a new file called staging.rb, add staging namespace in config files (copy from production most likely)
• update ansible-playbook to reflect this change.
• It should be the same setup as the production environment, only difference would be credentials etc in secrets.yml.