Implement the calendar_status

- Add the calendar_status when creating a new calendar
- Add the possibility to edit the calendar_status when editing a calendar
- Block adding, editing and removing meetings on calendars that are no longer active
Update the add and edit calendar page to include the calendar status
Only show in the side bar calendars that are active
Display separatly active calendars from un-active calendars
Add a method to retrieve calendar by their status
Fix the layout of the index page by performing two queries for both types of calendars

This allows to use a macro to rendre the table of calendar, simplying the template but
it ensures the layout of the index page remains correct while the first attempt was bugging
if the number of calendar activate/disabled was higher than 3.
Small layout change in the index page
Fix unit-tests; ignore a couple of place that we do not test
Fix copyright year
Rename get_calendar_status into get_calendar_statuses
There will likely be more than one calendar activated or disabled