create qrcode in the browser instead of an external service

While there zap a note that is obvious, because there is no button
and a text label saying what facility uses the cert...

The call stack is pretty loose on is_fqdn() as it is called by
system_routing_configure() which gets called in an uncontrollable
fashion in interface.inc.

This needs to be ported to the python backend table, because
this code requires nmap to be installed...

Instead of injecting dynamic gateways after reading the config, we will
inject them before instead.  This gives us the opportinuity to check
for matches and remove disabled gateways, finally addressing #933 in a
sane way.

Suggested by: @fabianfrz

Suggested by: @fabianfrz

created a fix for 914 (openvpn-client-export.inc)