Default DC & Cluster has fixed UUIDs

This patch modifies the uuid_generate_v1 function to have some
randomization in its least significant part so different engines will have
different UUID values from the generated default DC UUID and default
Cluster.

In addition This patch fixes a static data inserted as Cluster UUID for
the blank template.

I had tested generation of million UUIDs to verify its uniqueness just
for the case although the generation of the 29 most significant numbers
are still done by the sequence and supposed to be unique.

Change-Id: Ic5650fe1586fae320484f8cd36698491554efa57
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1026885
Signed-off-by: Eli Mesika <emesika@redhat.com>