Add support for group notes

Examples: School rules read out or Fire alarm rules tested

changed milestone to %1.0a1

added part::backend part::frontend prio::2 source::customer type::feature labels

added prio::1 label and removed prio::2 label

assigned to @nik

assigned to @debdolph and unassigned @nik

created merge request !65 (merged) to address this issue

mentioned in merge request !65 (merged)

closed via merge request !65 (merged)

mentioned in commit 30aea56d