[review] dcbw/vpn-routes-cleanup: fix disappearing VPN routes on address renewals

[Dan Williams <dcbw redhat com>]

Review appreciated, especially from Pavel.  I don't really like the
added parameter to nm_ipX_config_commit() but it's actually simpler code
than the alternatives, and we don't really want these routes in the main
IPXConfig objects because (a) they are transient and not really part of
the connection and (b) we'd have to remove them from the main IPConfig
when the VPN went down, and that's more complicated.

Thoughts?  This should fix the disappearing host route.

Dan