reduce dependence on mod_echo in t/dyups.t
bugfix that response of /detail uri has no Content-Length header

Get /detail response without header 'Content-Length', as following:
--- (Got response from failed dyups.t case.) ---
HTTP/1.1 200 OK
Server: Tengine/1.4.6
Date: Tue, 21 Jan 2014 09:16:04 GMT
Connection: close

host1
server 127.0.0.1:8088

host2
server 127.0.0.1:8089

dyhost
fix wrong string comparison for string "upstream"
Merge pull request #3 from chobits/bugfix