Revamp of email notifications

[dsajdak]

Email notifications are used alot in ColdFront but sometimes it's too much. We need a better way of managing emails. Among these changes are:

• A user should not get multiple emails in a day if they have multiple allocations expiring soon, for example. There should be a more intelligent way to combine all notifications into one.
• Admins should be able to make a one time change to allocation statuses and prevent an email from going out to users on that allocation.
• Admins should be able to turn off all notifications for a project and allocations permanently if desired.
• Allow configuration of notifications for allocations that expire to be sent to admins or support email
• Users should be able to adjust the types of notifications they receive on a system level in the User profile
• Add notifications for resources that are coming up on warranty expiration.
• Add notification for when user is added to a project

Related issues include:

• [x] #270
• [ ] #296
• [ ] #371
• [x] #289
• [x] #297

[dsajdak]

I'm removing from this original list issue #363 as we decided to deal with user profiles separately. There are alot of enhancements other CF users would like on this topic. I'm also removing #419 (editing email templates) as we decided to hold off on this one for awhile.