Add widget to persons page with (future) absences

Per default it should show a simple list of future Kolego absences. The widget should get the title Planned Absences. It should contain an option to delete absences and to edit their comment.

added part::frontend type::feature workflow::current-todo labels

assigned to @hansegucker

created branch 33-add-widget-to-persons-page-with-future-absences to address this issue

mentioned in merge request !54 (merged)

mentioned in commit a15cb370

closed with merge request !54 (merged)