Snap: Convert "save best" dialog text to a quantity string

* Saving 1 vs saving several can be a different string in other languages
 (e.g. German: "1 von 10 Bildern wird gespeichert[...]"
  vs "2 von 10 Bildern werden gespeichert[...]")
* Also fixes a missing "be" in the source string ("will _be_ deleted")

Change-Id: I0f0a91fa3cd1abe17c9d3eef453c4ed706a6fb25
2 files changed