support mounting CDROM on virtual machine by nova-api

As an administator or a virtual machine user, I want to install some solftware to the VM from my client. Therefore, I need to mount the virtual CDROM on the VM from the Dashboard, then I can install the ISO image(which was created from the solftware) through the virtual CDROM.
Now, I can mount the CDROM on the VM by using virsh commond on the physical host where the VM was deployed. Because of the need to log in the physical host, this is very inconvenient, sometimes also can't do it.
Additional need to do is to provide a restFul API and finished some supporting work in nova-compute service. Then I can mount the CDROM and use it from Dashboard or my client.