4118 libuuid should provide uuid_unparse_{upper,lower} functions

Reviewed by: Serghei Samsi <sscdvp@gmail.com>
Reviewed by: Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
Reviewed by: Robert Mustacchi <rm@joyent.com>
Reviewed by: Garrett D'Amore <garrett@damore.org>
Approved by: Dan McDonald <danmcd@omniti.com>