Merge branch 'negative_approvals' into 'master'

Fix bug with negative approvals required

https://gitlab.com/gitlab-org/gitlab-ee/issues/58

See merge request !72

CHANGELOG-EE

 v 8.3.0 (unreleased)
   - License information can now be retrieved via the API
+  - Fix bug with negative approvals required
 v 8.2.0
   - Invalidate stored jira password if the endpoint URL is changed

app/models/merge_request.rb

@@ -444,7 +444,7 @@ class MergeRequest < ActiveRecord::Base
   end
   def approved?
-    approvals_left.zero?
+    approvals_left < 1
   end
   def approved_by?(user)