Remove oslo uuidutils.generate_uuid() call

uuidutils.generate_uuid() is going to be removed from oslo, so we
need to remove the call from our Ironic code.
http://lists.openstack.org/pipermail/openstack-dev/2013-November/
018980.html
We create new method in our Ironic common utils to wrap the
generate_uuid methods.

Change-Id: I7bc4ca8fcdb29c4ee5b3e7fc7afb0235812a1c0d
Partial-Bug: #1253497