Fix foodcritic

This MR fixes all foodcritic issues and removes some unused attributes at the same time. More specifically,

• support_email - The support email is not used anymore in gitlab.
• standard_signin_enabled - The sign enabled feature is already covered by the signin_enabled attribute.

mentioned in merge request !110 (merged)

mentioned in merge request !111 (merged)

Reassigned to @marin

Milestone changed to 7.3

Thanks