qualify references to SP3 updates for clarity
ordering tweaks

It makes things more legible if we order in layers, starting with the
base OS, then the products after.
avoid a tiny bit of duplication
ensure Devel:Cloud:Shared:11-SP3:Update repo is mounted
add Cloud Updates repo
Merge pull request #37 from aspiers/cloud-updates

add SUSE-Cloud-3.0-Updates and Devel:Cloud:Shared:11-SP3:Update