This patch common.excutils from openstack-common, which includes
save_and_reraise_exception(). The patch also converts the code
base to use it from there instead of nova.utils and then removes
it from nova.utils.
The initial motivation for this was removing another nova dependency
from nova.rpc so that it can eventually be moved to openstack-common.
Change-Id: I7354ca51a02aec9c709cf33f77d4abc46acc2742