Support Ruby 2.2
Created by: chulkilee
This is a placeholder for issues on Ruby 2.2
- 500 when deleting a project: #8621 (closed) #8624 #8671
- 500 on admin/groups: #8590 (closed) #8685
- 500 when adding key or label: #8567 (closed)
Common pattern is undefined methodname' for nil:NilClass`