Check files that are not ready (file_locations -> file_location_ready) are actually OK

[digimer]

Ran into a bug where a file sync'ed (all jobs at 100% complete) but somehow the file_location_ready is left as false.

Have periodic checks that see if the file exists and, if so and there's no sync jobs pending, call file_sync_shared (or whatever tool is best) to verify the sum and marks it as ready.