Add notifications of events

[Coding-Cactus]

• [x] Browser notification for new messages if website isn't focused
• [x] Chat unread messages count
• [x] Update page title to reflect notifications
• [x] Send email notifications for contact request updates
• [x] Send push notification for being added to a chat
• [ ] Notifications preference page

[DillonB07]

Showing a count of unread messages next to chats would also be great