vstart.sh: --hitset <pool> <type>

Signed-off-by: Sage Weil <sage@inktank.com>
osd/ReplicatedPG: set object_info_t, SnapSet on hit_set objects

These are first-class user-visible rados objects and need these attrs.

Signed-off-by: Sage Weil <sage@inktank.com>
osd/ReplicatedPG: maintain stats for the hit_set_* objects

We also make hit_set.current_info reflect only the on-disk 'current', not
anything that is not persisted.

Signed-off-by: Sage Weil <sage@inktank.com>
osd/ReplicatedPG: drop unused hit_set_start_stats

Signed-off-by: Sage Weil <sage@inktank.com>
test_ipaddr: add another unit test

Was checking something for kbader.

Signed-off-by: Sage Weil <sage@inktank.com>