Modified the default HTTP headers used by libcurl:

A) Normal non-proxy HTTP:

 - no more "Pragma: no-cache" (this only makes sense to proxies)

B) Non-CONNECT HTTP request over proxy:

 - "Pragma: no-cache" is used (like before)
 - "Proxy-Connection: Keep-alive" (for older style 1.0-proxies)

C) CONNECT HTTP request over proxy:

 - "Host: [name]:[port]"
 - "Proxy-Connection: Keep-alive"

tests/data/test163

@@ -43,7 +43,6 @@ yes please
 POST /we/want/163 HTTP/1.1
 User-Agent: curl/7.11.2-CVS (i686-pc-linux-gnu) libcurl/7.11.2-CVS OpenSSL/0.9.6b zlib/1.1.4 c-ares/1.0.0
 Host: 127.0.0.1:%HTTPPORT
-Pragma: no-cache
 Accept: */*
 Content-Length: 304
 Expect: 100-continue