Add log page support to nvmecontrol(8) through a new logpage command.

This includes pretty printers for all of the standard NVMe log pages
(Error, SMART/Health, Firmware), as well as hex output for non-standard
or vendor-specific log pages.

Submitted by: Joe Golio <joseph.golio@emc.com>
Obtained from: EMC / Isilon Storage Division
MFC after: 3 days