Since a network interface cannot change.

Define a decorator for libvirt handlers, those can be used only when the
connection to the libvirt is active

The tag was not removed from TagDB when the libvirt connection was lost.

Only one network interface was shown in the tags.

With the permission of Romain Degez, CTO of Smartjog.

Signed-off-by: Sébastien Luttringer <sebastien.luttringer@smartjog.com>

Libvirtd version 0.8.8 is capable of handling connections to virtio consoles but
the Python API is broken.

Tunnel endpoints are now automaticaly closed by default.

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.