[gphotoframe/f18] (3 commits) ...Fix yet another case on exif information with zero denominator

[Mamoru Tasaka]

Summary of changes:

  3114b7a... Fix traceback when choosing photo source on setting gui (*)
  1253a92... Merge remote-tracking branch 'origin/master' into f18
  6f79e33... Fix yet another case on exif information with zero denomina

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