Use xmlschema date format (ISO 8601) on system hooks timestamp
Official document (http://doc.gitlab.com/ce/api/system_hooks.html) says created_on
date in system hook json should follow ISO 8601, but it doesn't.
This PR fixes that.
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
Official document (http://doc.gitlab.com/ce/api/system_hooks.html) says created_on
date in system hook json should follow ISO 8601, but it doesn't.
This PR fixes that.