empty input when the user has been invited to the topic
create /topic/<id>/collaborators API endpoint
can retrieve collaborators from Topic service
resolve collaborators in invite ctrl
start collaborators list
collaborators list
can make someone leave a topic
link trash icon to delete function in collaborators link
update collaborators list on addition/deletion
owner always on top
check authorization before update collaborators list
create an administrator group on topic creation
add data migration for administrator group creation
add a Group service and use it everywhere
Implemented 'make topic private' feature #617
load admin groups on dashboard and check rights before including 'collaborators' button
update admingroups when loading another page
create /topic/<id>/administrators/ endpoint
load administrators on collaborators page
show admins in table