tasks: ensure we run at max N jobs and not N+1
cloud ops: handle each node just once with the right provider

Previously the same node could appear multiple times on the list.
Also, all of the nodes were handed on to all of the providers instead
of passing provider specific lists the the relevant cloud backends.
libvirt: handle all vm operations in parallel
tool: make expects_obj the first decorator to avoid warnings

New argh emits a warning whenever @argh.arg or @argh.named is used if
@argh.expects_obj has not yet been used so always call it first.
Merge branch 'fsc' of git://github.com/saaros/poni

* 'fsc' of git://github.com/saaros/poni:
  tool: make expects_obj the first decorator to avoid warnings
  libvirt: handle all vm operations in parallel
  cloud ops: handle each node just once with the right provider
  tasks: ensure we run at max N jobs and not N+1