Check disk space before sending to VMware

[chris1984]

When we create a VM as a fallback we should check the diskspace on a datastore/storage_pod before we commit and if there is not enough space left we fail and alert Foreman or the user if Foreman is not being used.

[ezr-ondrej]

Or we can just make the cloning on the storagePods atomic again - meaning delete the created machine.