Add .docker/config.json and support for HTTP Headers

This PR does the following:
- migrated ~/.dockerfg to ~/.docker/config.json. The data is migrated
  but the old file remains in case its needed
- moves the auth json in that fie into an "auth" property so we can add new
  top-level properties w/o messing with the auth stuff
- adds support for an HttpHeaders property in ~/.docker/config.json
  which adds these http headers to all msgs from the cli

In a follow-on PR I'll move the config file process out from under
"registry" since it not specific to that any more. I didn't do it here
because I wanted the diff to be smaller so people can make sure I didn't
break/miss any auth code during my edits.

Signed-off-by: Doug Davis <dug@us.ibm.com>
Upstream-commit: 18c9b6c6455f116ae59cde8544413b3d7d294a5e
Component: engine

components/engine/api/client/cli.go

@@ -9,6 +9,7 @@ import (
 	"net"
 	"net/http"
 	"os"
+	"path/filepath"
 	"reflect"
 	"strings"
 	"text/template"
@@ -120,14 +121,6 @@ func (cli *DockerCli) Subcmd(name, signature, description string, exitOnError bo
 	return flags
 }
 
-func (cli *DockerCli) LoadConfigFile() (err error) {
-	cli.configFile, err = registry.LoadConfig(homedir.Get())
-	if err != nil {
-		fmt.Fprintf(cli.err, "WARNING: %s\n", err)
-	}
-	return err
-}
-
 func (cli *DockerCli) CheckTtyInput(attachStdin, ttyMode bool) error {
 	// In order to attach to a container tty, input stream for the client must
 	// be a tty itself: redirecting or piping the client standard input is
@@ -184,9 +177,15 @@ func NewDockerCli(in io.ReadCloser, out, err io.Writer, keyFile string, proto, a
 		tr.Dial = (&net.Dialer{Timeout: timeout}).Dial
 	}
 
+	configFile, e := registry.LoadConfig(filepath.Join(homedir.Get(), ".docker"))
+	if e != nil {
+		fmt.Fprintf(err, "WARNING: Error loading config file:%v\n", e)
+	}
+
 	return &DockerCli{
 		proto:         proto,
 		addr:          addr,
+		configFile:    configFile,
 		in:            in,
 		out:           out,
 		err:           err,