CS used to access vnc server in xenserver dom0 to get VM console, now CS moves to use XenServer console API. getvncport plugin is not needed any more.
remove the code related to getvncport in XenServer
Detail: KVM recently got a patch that did away with a few dozen ssh calls
when programming virtual router (CLOUDSTACK-3163), saving several seconds
for each vm served by the virtual router when the router is rebooted. This
patch updates Xen to use the same method, and cleans up the old script refs.
Reviewed-by: Sheng Yang, Prasanna Santhanam
