SUSE-CLOUD-3-DEPS FTW! Dirk rules!

Dirk built a replacement for the standard SLES11 SP3 installation media
which is a cut-down version of SP3 only containing the packages which
Cloud 3 requires, and with all the latest updates embedded.

So this means we don't have to embed the whole of SP3 and its updates in
the appliance any more :-D
switch to latest Devel:Cloud:3:Staging iso
SUSE-CLOUD-3-DEPS now includes HAE packages too
add zerofree
indent to 4 columns for consistency
remove kernel headers if guest additions successfully installed

The kernel headers actually take up quite a bit of disk which we can
potentially save using zerofree.
fix /etc/hosts
reduce tmpfs requirement now we are using -DEPS
explain why we still use SP3 and SP3-Updates
improve ordering of packages in config.xml
update and add READMEs to deal with two appliances / boxes
add SLES11 SP3 vagrant box definition
add idea for how to add data disks
tidy up comments