Environment-specific variables

Merged Lin Jen-Shin requested to merge 2302-environment-specific-variables into master

What does this MR do?

Implement environment-specific variables

Screenshots (if relevant)

Screen_Shot_2017-06-15_at_21.18.16

Does this MR meet the acceptance criteria?

TODO:

  • Update doc to be consistent with protected_branches/tags
  • Decide if we should go with scope or say, environment_name
  • Backport to CE

What are the relevant issue numbers?

Closes #2302 (closed)

Edited by Lin Jen-Shin