Derived from the ipsec initd script, with the following changes:
(1) various code improvements, corrections (get rid of left/right
updown scripts, since there's only one), etc;
(2) add reauth and fragmentation parameters;
(3) add x.509 certificate-based authentication;
and other minor changes.
Signed-off-by: Philip Prindeville <philipp@redfish-solutions.com>