Added the ability to configure ipTunnel connections.

The only addition that isn't particularly obvious is the addition of luci-cjdns/luasrc/view/cjdns/value.htm. It's basically an exact copy of the default value template in LuCI. The only thing I changed was adding the width  auto style on line 5. Without that, the size set on the Value option (e.g. line 33 in iptunnel.lua) is ignored.