Added code and unit tests for editing calendars in the CalDAV object

Added code and unit tests for editing calendars in the CalDAV object

Added the following subroutines to the CalDAV object:

EditCalendarProcess(*string, *string, *Colour, *string, *int);
EditCalendar(*string, *string, *Colour, *string, *int);
EditCalendar(*string, *Colour);
EditCalendar(*string, *string);
EditCalendar(*string, *int);
EditCalendarDescription(*string, *string);

Unit tests setup for editing calendars under CalDAV/EditCalendar testing
the above functions.