refactor model: Create a separated model for task resource

To avoid duplicating code in model and mockmodel, the common code related to
task resource was added to model_/tasks.py and the specific code for each
backend was added to model_/backend/ model_/mockbackend/

The model_ module is a temporary one, as there already is a module named model
in source code. When start using the new code, model_ will be renamed to model
and the former model.py deleted.

Signed-off-by: Aline Manera <alinefm@br.ibm.com>
refactor model: Create a separated model for plugin resource

To avoid duplicating code in model and mockmodel, the code related to
plugin resource was added to model_/plugins.py

Signed-off-by: Aline Manera <alinefm@br.ibm.com>
refactor model: Create a separated model for debugreport resource

To avoid duplicating code in model and mockmodel, the common code related to
debugreport resource was added to model_/debugreports.py and the specific code
for each backend was added to backend/debugreports.py and
mockbackend/debugreports.py

Signed-off-by: Aline Manera <alinefm@br.ibm.com>
refactor model: Create a separated model for config resource

To avoid duplicating code in model and mockmodel, the common code related to
config resource (and its sub-resources) was added to model_/config.py
and the specific code for each backend was added to backend/config.py
and mockbackend/config.py

Signed-off-by: Aline Manera <alinefm@br.ibm.com>
refactor model: Create a separated model for host resource

To avoid duplicating code in model and mockmodel, the common code related to
host resource (and its sub-resources) was added to model_/host.py and
the specific code for each backend was added to backend/config.py and
mockbackend/config.py

Signed-off-by: Aline Manera <alinefm@br.ibm.com>
refactor model: Create a separated model for libvirt connection

Libvirt connection is a base facility for kimchi model, so each
resource model should be able to access it directly.

Signed-off-by: Aline Manera <alinefm@br.ibm.com>
refactor model: Move StoragePooldef from model to libvirtstoragepools.py

Separate StoragePoolDef (and its sub-classes) from model as it handles the xml
generation for libvirt storage pools.

Signed-off-by: Aline Manera <alinefm@br.ibm.com>
refactor model: Create a separated model for storagepool resource

To avoid duplicating code in model and mockmodel, the code related to
storagepool resource was added to model_/storagepools.py and
the specific code for each backend (libvirt or mock) was added to
backend/storagepools.py and mockbackend/storagepools.py

Signed-off-by: Aline Manera <alinefm@br.ibm.com>