fix vpn payload base to have correct string interpolation
fix ncs vpn connection manager init
add missing import in ncs vpn test
always return a deferred from httpRequest
ncsvpn backend: make sure that service url is a string
on second though, moving string conversion into connection manager
ncs vpn backend: do vlan check + target convert right, and add functionality to create connection id
add notification about link being down in ncs vpn backend