gtk: add translation support (v5)

This includes a de_DE translation from Kevin Wolf and an it translation from
Paolo Bonzini.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>
Cc: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Message-id: 1361367806-4599-8-git-send-email-aliguori@us.ibm.com