Allowing target state for evacuate

This is to enhance the evacuate instance API to allow operator setting target state.

In certain circumstances the operator may have desire when evacuating running instances from a service down to set target state as stop even if they were considered as running in the source host.

It’s for example the usage for some public clouds like Amazon AWS.

The enhanced API will now provide the ability to set TargetState as (Current, Running, Sopped) where the default will remain Current.