[mate-screensaver/f17] (4 commits) ...Merge branch 'master' into f17

[Dan Mashal]

Summary of changes:

  5a50333... only allow one instance per user, fix dual login prompt (*)
  90ed185... fix release, bump (*)
  c59743d... conditionals to use systemd or CK depending on fedora versi (*)
  05a4241... Merge branch 'master' into f17

(*) This commit already existed in another branch; no separate mail sent