fix entries of hop-by-hop header (#311)

Remove unnecessary headers

Proxy-Authorization and TE are request headers, not response.

Author: shigeki

packager/util/http.go

@@ -36,9 +36,7 @@ var legacyHeaders = map[string]bool{
 	"Connection": true,
 	"Keep-Alive": true,
 	"Proxy-Authenticate": true,
-	"Proxy-Authorization": true,
 	"Proxy-Connection": true,
-	"TE": true,
 	"Trailer": true,
 	"Transfer-Encoding": true,
 	"Upgrade": true,