Update the readme to include the build status and links to the output.

I've had a few requests for helping building the code or asking for a precompiled assembly. Would be nice to go ahead and get a Chocolatey (see Chocolatey.org) package built so people can just use that, just need to update the config file as appropriate.

Started using the AppVeyor CI for builds, wouldn't be too hard to push the result of that to Chocolatey.

The updater is not working for my domains and I'm not sure why. I created A records for 4 sub-domains I want to update and put them as CSV values in the app.config file, as well as my API key and my DH user name. When I start the update service the log shows the following information. There are no errors but it doesn't seem to complete its task:

2017-07-25 15:38:07.0835|INFO|DHDns.Service.Program+TaskService|Starting Dynamic DNS Update Service...
2017-07-25 15:38:07.1281|INFO|DHDns.Library.UpdateJob|Starting UpdateJob...
2017-07-25 15:38:07.5574|INFO|DHDns.Library.UpdateJob|Retrieved current IP: XXX.XXX.XXX.XXX

Some information on how to set this up would be helpful.

It looks like some information is needed in the Service/App.config (api key, dh user, hostname, logfile) but it's not defined anywhere. Also, is there any setup I need to do in my DH account? It seems I need the API key but anything else? I think I have it all set up on my pc but not sure if I need to define the subdomain before it will work correctly; if so, info on how to do that would be helpful. Also, the items necessary for the API key to have enabled would be useful, too.

Other than that, thanks for the very helpful project; hopefully my initial attempt at getting this working works okay and I don't need the info above!