Add X-Registry-Config support

* Refactor auth pkg to support X-Registry-Config
* Refactor build endpoint to support X-Registry-Config. Supports:
  * --creds
  * --authfile
* Added X-Reference-Id Header to http.Request to support log event
  correlation
* Log headers from http.Request

Signed-off-by: Jhon Honce <jhonce@redhat.com>

vendor/google.golang.org/appengine/internal/api.go

@@ -58,8 +58,11 @@ var (
 
 	apiHTTPClient = &http.Client{
 		Transport: &http.Transport{
-			Proxy: http.ProxyFromEnvironment,
-			Dial:  limitDial,
+			Proxy:               http.ProxyFromEnvironment,
+			Dial:                limitDial,
+			MaxIdleConns:        1000,
+			MaxIdleConnsPerHost: 10000,
+			IdleConnTimeout:     90 * time.Second,
 		},
 	}