ovpn_run: Explicitly enable ipv6

On a recent build I ran in to the following error messages:

    Wed May  3 14:31:43 2017 /sbin/ip -6 addr add 2001:db8:0:4::1/64 dev tun0
    Wed May  3 14:31:43 2017 Linux ip -6 addr add failed: external program exited with error status: 2

This appears to be do to the fact that somewhere something defaulted the
kernel in the container to disable IPv6.  Not sure if this is my host or
the docker daemon.  Re-enable it explicitly for now until Docker gets
it's IPv6 act together.

Author: kylemanna

bin/ovpn_run

@@ -90,6 +90,7 @@ if [ $? = 0 ]; then
     # If this fails, ensure the docker container is run with --privileged
     # Could be side stepped with `ip netns` madness to drop privileged flag
 
+    sysctl -w net.ipv6.conf.all.disable_ipv6=0 || echo "Failed to enable IPv6 support"
     sysctl -w net.ipv6.conf.default.forwarding=1 || echo "Failed to enable IPv6 Forwarding default"
     sysctl -w net.ipv6.conf.all.forwarding=1 || echo "Failed to enable IPv6 Forwarding"
 fi