ovpnmain.cgi: Restart instead of reload

ovpnmain.cgi: Restart instead of reload

The option to reload the server does not seem to work well. The running
is process is performing a number of checks that make very little sense
and PID files get written by the user that launches the process (i.e.
root) instead of the user that the process is running as later on (i.e.
nobody). Since there is no chance to keep any existing connections alive
this way, we may just as well restart the service for now.

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>