Update edit.html.haml

Pluralization in some latin languages fails otherwise. Corresponding yaml must be changed to:
en:
  admin:
    cms:
      layouts:
        edit:
          revision:
            zero: no revisions
            one: 1 revision
            other: %{count} revisions

that in Italian, for example, would be:

it:
  admin:
    cms:
      layouts:
        edit:
          revision:
            zero: nessuna revisione
            one: 1 revisione
            other: %{count} revisioni