ostree: Log status updates of pull
ostree: Log status updates of pull

Fixes https://github.com/advancedtelematic/aktualizr/issues/670

The changes produce output at loglevel INFO like:

 ostree-pull: Receiving metadata objects: 3
 ostree-pull: Receiving metadata objects: 4
 ostree-pull: Receiving metadata objects: 6
 ostree-pull: Receiving metadata objects: 9
 ostree-pull: Receiving metadata objects: 11
 ostree-pull: Receiving objects: 44%
 ostree-pull: Receiving objects: 83%
 ostree-pull: Receiving objects: 90%
 ostree-pull: Receiving objects: 93%
 ostree-pull: Receiving objects: 97%
 ostree-pull: Writing objects: 1
 ostree-pull: 13 metadata, 16 content objects fetched; 44683 KiB transferred in 23 seconds

Signed-off-by: Andy Doan <e3579b1e47f273529f0f929453e939a68ede9fd1@opensourcefoundries.com>

advancedtelematic/aktualizr,advancedtelematic/aktualizr,advancedtelematic/aktualizr,advancedtelematic/sota_client_cpp,advancedtelematic/aktualizr,advancedtelematic/sota_client_cpp