fix ordering of sudo package
ditch SLE-11-SP3-SDK-Updates

None of the packages we get from SDK have updates (and even if they
do later, we probably don't need them).
we should be able to live without SLES11-SP3-Updates

With the quick way of building, the important updates are
already in SUSE-CLOUD-3-DEPS.
document both fast and slow ways of building images