Add Devel:Cloud:Shared:11-SP3.repo

IBS repo layout changed recently. Set some priorities to make sure
Devel:Cloud projects overrule SLE repos and install media.
Configurable path for mirrored media

Control freaks mirror media to various directories (like /srv/nfs/media)
and want to expose that to VM guests.
Fix SP3-Pool/-Update mirrored mountpoints

There are no "sle-11-sp3" sub-directories.