Don't show blockings in booking quick searches
Added decorator for sending email notifications
Refactored booking notifications

* Moved notification methods to rb.notifications module
* Moved email templates to jinja and modularized them
Prevented fetching many occurrences
Typos and rewording
Moved email templates to a dedicated folder
Removed some debug statements
More semantic expressions
Small fixes and code cleanup

* Renamed some methods and files
* Replaced to lowercase true/false/none in jinja templates
* Prevented some unnecesary queries
* Small rewording in templates
* Addapted missing template to jinja
* Fixed broken link to videoconference survey
Moved RB blockings email to jinja
Videoconference survey url replaced with short one
Generalized email templates a bit more
Fixed rejecting bookings on blocking approval

Also, adding edit_log is not needed anymore as it's taken care by the
Reservation and ReservationOccurrence reject() methods
Use HTTPS link for the AVC survey
Remove some unused code (is_heavy & some imports)
Fix invalid if condition in blocking notification