Add support for ddclient (using freedns right now)

Dynamic DNS services, like freedns, allow us an easy way to setup a test
domain without actually having to pay for it. This will be useful for
testing email functionality.
Add "casual" mode for openttd server

This is a set of pre-picked "easier" settings. This includes a smaller
map, more loan allowance, lower loan interest, and a flat-ish landscape.