The activity owner should only be visible to registered members, not to guests.
Display an activity's editors.
Grant editors the right to edit their activity.
Editors can now be edited and persisted.
Extended gitignores.
Allows to properly display 500 errors in tests.
Fixed some errors, added tests.
Tests for editing.
Adapted test to formatted HTML as produced by Travis (wtf?)
Merge pull request #831 from NicoleRauch/master

Activities can now have editors