- This ensures content notifications are not translated to receiver
language.
- This adds actual plaintext support for content notifications (Was
previously just HTML as text view).
- Shares same base class across all mail notifications.
- Also cleaned up existing notification classes.
Future cleanup requested via #4501
* Started move to laravel 5.3
* Started updating login & registration flows for laravel 5.3 update
* Updated app emails to notification system
* Fixed registations bugs and removed email confirmation model
* Fixed large portion of laravel post-upgrade issues
* Fixed and tested LDAP process