Removed the 'wait for GCE metadata service' job, as it was causing
issues with the metadata service (likely some firewall or something).
In stead, use wget with retries (including connection refused) in
stead or curl for fetching the SSH keys. Also made the stdout/-err
of this job appear in the console.
Using pkgs.lib on the spine of module evaluation is problematic
because the pkgs argument depends on the result of module
evaluation. To prevent an infinite recursion, pkgs and some of the
modules are evaluated twice, which is inefficient. Using ‘with lib’
prevents this problem.
