Modified loadbalancer call to VncApi by adding more parameters for authentication.
plugin will get additional parameter from its conf file and in case of NoSuchOptError
will pass default to VncApi(). This was needed when config node and openstack node were
separate and neutron is unable to read vnc_api_lib.ini file. Now neutron will not depend
on api_lib.ini or its default

Change-Id: I973124a8d5c734f9f16923794a2fba6648b8ad2a