rgw: remove s->objv_tracker

was never initialized correctly anyway. It was only supposed to
be used for buckets, but it was never initialized in that case.
Using s->bucket_info.objv_tracker instead.

Signed-off-by: Yehuda Sadeh <yehuda@inktank.com>
rgw: bucket entry point object ver fixes

Multiple fixes:
 - sync master, secondary entry point ver on creation
 - use correct entry point version when removing entry point
 - check correct version on bucket removal

Signed-off-by: Yehuda Sadeh <yehuda@inktank.com>