add some Test::TCP-based tests from Dancer 1

in GH-109 @sukria suggested that I could port tests from Dancer 1 which rely on Test::TCP. 

I tried now  for a couple of days, but it seems that I can't do it alone. There are a bit too many things involved here at once for me. Perhaps someone can help me and point me in the right direction. Either per mail or in this issue. Or how you prefer.

Right now several of the tests suggested in this PR don't pass. It looks to me like Dancer2 is not behaving correctly, but I am not at all sure about that. 

Hope that Travis will produce meaningful error reports. Let me know how and where I should continue. 

Thanks!