Added iCloud Mail

[chrisharper22]

This adds the new iCloud Mail sub-menus mentioned in issue #58.

• iCloud → iCloud Mail → (root): prefs:root=APPLE_ACCOUNT&path=ICLOUD_SERVICE/com.apple.Dataclass.Mail
• iCloud → iCloud Mail → Default Email: prefs:root=APPLE_ACCOUNT&path=ICLOUD_SERVICE/com.apple.Dataclass.Mail/DEFAULT_EMAIL
• iCloud → iCloud Mail → Addresses: refs:root=APPLE_ACCOUNT&path=ICLOUD_SERVICE/com.apple.Dataclass.Mail/ALIASES
• iCloud → iCloud Mail → Auto-Reply: prefs:root=APPLE_ACCOUNT&path=ICLOUD_SERVICE/com.apple.Dataclass.Mail/AUTO_REPLY
• iCloud → iCloud Mail → iCloud Mail Rules: prefs:root=APPLE_ACCOUNT&path=ICLOUD_SERVICE/com.apple.Dataclass.Mail/SERVER_SIDE_RULES
• iCloud → iCloud Mail → Mail Forwarding: refs:root=APPLE_ACCOUNT&path=ICLOUD_SERVICE/com.apple.Dataclass.Mail/MAIL_FORWARDING
• iCloud → iCloud Mail → Mailbox Behaviors: prefs:root=APPLE_ACCOUNT&path=ICLOUD_SERVICE/com.apple.Dataclass.Mail/MAILBOX_BEHAVIORS
• iCloud → iCloud Mail → Signing and Encryption: prefs:root=APPLE_ACCOUNT&path=ICLOUD_SERVICE/com.apple.Dataclass.Mail/S_MIME
• iCloud → iCloud Mail → Import Messages: prefs:root=APPLE_ACCOUNT&path=ICLOUD_SERVICE/com.apple.Dataclass.Mail/MAIL_IMPORT