Fix bug with routes when gateway resolved to multiple IP addresses. Plugin pre-resolv address self and then pass resolved IP to xl2tpd.

FIXME: fix ugly routes parser

Feature: write "port" option to xl2tpd config. Check that this port is not used, if used - use "0" as port value.

replace NM_L2TP_KEY_USE_ACCOMP to NM_L2TP_KEY_NO_ACCOMP for consistency (may require user to re-save his ppp options)