Guest disk hot plug UI

V3 -> v4:
Disable CDROM hotplug due to back-end limitatiions

V2 -> V3:
Minor changes according to JQuery rules.

V1 -> V2:
Enable CDROM hot plug including detaching.

Enable users add and detach disk when vm is running.

Signed-off-by: Wen Wang <wenwang@linux.vnet.ibm.com>