Import-Export Instances on KVM

The project adds support for importing and exporting virtual machines (VMs) from KVM Hypervisor into the CloudStack. It helps administrators better manage resources and transfer VMs if needed. The CloudStack currently supports this functionality only on VMWare and support on KVM (as one of the most popular open source hypervisor) can tremendously help many other users of CloudStack. In terms of deliverables the following can be expected at the minimum: 1. Implement/extend listUnmanagedInstances API: Lists unmanaged virtual machines (not existing in CloudStack but existing on the hypervisor side) 2. Implement/extend importUnmanagedInstance: Import an unmanaged VM into CloudStack (this implies populating the database with the corresponding data) 3. Implement/extend unmanageVirtualMachine: Make CloudStack forget a VM but do not remove it on the hypervisor side 4. UI Changes to facilitate above API use through the web portal 5. Integration tests and documentations for ease of use