move mock classes in dedicated file
move MockConfigurationLoader in Mock.py
improved mock of Libvirt classes

Mock of virConnect.*CreateXML() have a better behaviour now with real
creation of Mock objects with xml parsing in there.
Also added methods in mock of virStoragePool, virNetwork and virDomain
for all methods used outside VirtController class.
added param to inject conf loader in Cloubed class

New named parameter 'conf_loader' on Cloubed class to inject an
optional configuration loader. This aims to help unit testing this
class.
add unit tests for Cloubed class