Do not generate client side hashes for small files (<2048 bytes)
Do not generate client side hashes for small files (<2048 bytes)

(cherry picked from commit 5a1a715df370a45086c33eeca56f52bae596c024)

uroni/urbackup_backend,uroni/urbackup_backend,uroni/urbackup_backend,uroni/urbackup_backend,uroni/urbackup_backend,uroni/urbackup_backend,uroni/urbackup_backend