Description of problem:
rebuild repository on group project does not work, because it create action for user owning project instead of group itself.


Steps to Reproduce:
1. user foo create group project @bar/xyz
2. check in "settings" tab "create repo manualy"
3. got to "Overview" and hit "Regenerate"
4. check /backend/waiting/ page

Actual results:
action:
    {
      "action_type": 3, 
      "created_on": 1460206148, 
      "data": "{\"username\": \"foo\", \"projectname\": \"xyz\",

Expected results:
    {
      "action_type": 3, 
      "created_on": 1460206148, 
      "data": "{\"username\": \"@bar\", \"projectname\": \"xyz\",