Use i-buttons on room details page
Cache lazy-loaded room properties

This provides a major speedup for pages which need those properties for
many rooms
Mention the new caching tools in DEVELOPMENT.md
Reservation actions are now working

* Accept, reject and cancel reservation
* Reject and cancel occurrences
* Actions stored in edit_logs
Set min date for end date datepicker on init
Hide link to show more log entries if only one
Special mail for daily repetition notifications