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/test33

@@ -49,7 +49,6 @@ PUT /33 HTTP/1.1
 Content-Range: bytes 50-99/100
 User-Agent: curl/7.6 (sparc-sun-solaris2.7) libcurl 7.6-pre4 (SSL 0.9.6) (krb4 enabled)
 Host: 127.0.0.1:%HTTPPORT
-Pragma: no-cache
 Accept: */*
 Content-Length: 50
 Expect: 100-continue