Fleshed out Notifications with priority enhancements

Large update that fixes major bugs with existing functionality, adds infrastructure that exposes more options for customization, and implements email notifications for priority 1 items.

Bugs
* emails were sent out erroneously when users failed to enter their profile info
* lack of distinction between audiences in delivery generation meant that all users would have to be notified of an action identically rather than receive a custom email related to their role in the action or entity acted upon

Enhancements
* Enhanced email and notification configurations to structure data in a deeper fashion, allowing for more customization options
* Added more content to configurations and services so that more actions are able to be triggered
* Added triggered email actions to projects and tasks upon commenting and volunteering
* Added email controller to return mailto link for client-side href generation. Eventually this will be an option along with server-side html email
* Added ability to generate prefilled text emails for profile, project, and task pages