Revert "OBMFULL-4633"

This reverts commit 73e9a79b93a09f122fa33d9d83c67280992b1f85.
OBMFULL-4633 Handle ICS COUNT property when displaying remote calendars.
OBMFULL-4633 RecurrenceKind computation refactor.

Put the RecurrenceKind value in its own variable, and assigns it in a single
location. This will allow us to rely on its value in other methods more
robustly, without having to worry about the possibility that it hasn't been
assigned yet in Event.
OBMFULL-4633 Moves RecurrenceKind computation to its own method.
OBMFULL-4633 Handle ICS COUNT property when importing an ICS.
OBMFULL-4633 Ical4jHelper returns rejected ICS too.

Instead of returning only events successfully parsed, Ical4jHelper also returns
rejects.
OBMFULL-4633 Ensure invalid rules throw exceptions, add tests.
OBMFULL-4633 Fix OBMFULL-2940 test.

Don't just that a list is not null.
OBMFULL-4633 Ensure rejected items throw an error.
OBMFULL-4633 Migrates to assertj.