Added the type in the method signature in cc-common.

Moved to cc-common

Was using a closure for tag function thus storage variable was always
referencing the last value of the iteration.

hypervisor/__init__.py ->
    hypervisor/__init__.py (Handler)
    hypervisor/kvm.py (Hypervisor -> KVM)
    hypervisor/lib.py (Storage*/Volume)

Replaced all logger call in child.
Added dedicated libev loop.
Handle exceptions using fatal helpers of ForkedJob.

Replace logging calls with sys.stderr.write in order to prevent deadlock in the
fork.

Indicates if driver used for disk backing is using some sort of caching which
may lead to data corruption for a live migration.

This prevents client libvirt version 0.8.8 to segfault when reseting libvirt
event handlers.

sending events on removed domains or sending removed event too late.

Sometimes, libvirt tells us too late that a domain has been removed.