vsphere: Handle more than 100 objects in esx traversal

RetrievePropertiesEx might return just partial result and virt-who now
calls ContinueRetrievePropertiesEx in order to get all results.
Add satellite support

Support also satellite as subscription manager (for hypervisor mode
only).
Fix syntax for python 2.4
Handle exceptions in virt_notify function
spec: create /var dir in the spec instead of source

Also install virt-who-register-satellite
register one system per hypervisor

Previously, each cluster was registered as a single system. Instead, register
each hypervisor individually.

Also, use more descriptive hypervisor system names that include UUID and virt
type.
Require username to be present

Username is now required because new hypervisor may appear anytime
Optimize creating satellite plan a little
use 'sam' as smType, not 'rhsm'
Get rid of all mentions of virt-who-register-satellite
Fix typo in README
Set SAM mode as default (in order to maintain backward compatibility)
Fix getting more results from ESX
1002447: log message when no hypervisors are found