Config option to control reusing http connection

Observed that in some cases the connection cannot be reused. Absent
detail analysis this appears random and it happens often enough
that the delay from waiting to retry is longer than any savings
derived from reusing.
Restore file attributes (s3cmd-attrs) on get

If user/group requires root privilege, only one warning is
issued and everything else proceeds normally.
Version with config for reuse connections and restore attrs on get