Upgrade to 0.8.0:

• Replace Jansson with YAJL for JSON rendering, which results in a substantial performance improvement.
• dnstable_dump: Add "--rrset_names" and "--rdata_names" options which dump the RRSET_NAME_FWD and RDATA_NAME_REV indices.
• New function dnstable_reader_reload_setfile(), which calls mtbl_fileset_reload_now() on a dnstable_reader object's underlying mtbl_fileset object, if present. This requires libmtbl >= 0.8.0.

Sponsored by: Farsight Security, Inc.