add kerberos dependency
Fix random Argument error when update note

In some strange cases Ruby thinks `system` is not AR field but
Kernel.system call and raises exception during save. It should prevent
this random wierd behaviour

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>
Merge branch 'fix-note-update' into 'master'

Fix note update

In some strange cases Ruby thinks `system` is not AR field but
Kernel.system call and raises exception during save. It should prevent
this random wierd behaviour.

Exception log:

```
ArgumentError (wrong number of arguments (0 for 1+)):
  app/models/note.rb:505:in `system'
  app/models/note.rb:505:in `editable?'
  app/controllers/projects/notes_controller.rb:33:in `update'
```

See merge request !1326
Merge branch 'master' of github.com:gitlabhq/gitlabhq
Merge branch 'kerberos_dependency' into 'master'

Kerberos dependency

See merge request !1324
Merge branch 'master' of dev.gitlab.org:gitlab/gitlabhq