Change GET query parameters to be more compact

[mcmanus]

closes issue #7

[roryhewitt]

I like the change to 'ct' for Content-Type, but I think 'body' is important enough where reducing it by only two bytes to 'rb' isn't worth the change. Perhaps there could be an abbreviated 'ct' value - e.g. 'ct=du'? Or, if 'ct' is not specified, then 'application/dns-udpwireformat' iMUST be assumed by the DNS server?

[mcmanus]

I could go either way on body. You're right that the actual mime type is a bit of a problem.. I'll try it with a ct name argument without a value having the default meaning. I think that's explicit enough, while I don't really like totally implicit things like the absence of ct (what if you mis-spell it?)

[roryhewitt]

@mcmanus Actually what was the reasoning behind passing Content-Type as a query parameter instead of as the Content-Type header? Presumably any DNS API server must be able to parse headers...

[mcmanus]

Content-Type as a header refers to the message payload which isn't what we're trying to describe here.. (its used on POST, where it matches..)