Allow updating chart dependencies when packaging a chart

Added -u flag that would cause helm dep up before running helm package

Fixes https://github.com/kubernetes/helm/issues/2128

cmd/helm/package.go

@@ -55,6 +55,7 @@ type packageCmd struct {
 	keyring          string
 	version          string
 	destination      string
+	dependencyUpdate bool
 
 	out  io.Writer
 	home helmpath.Home
@@ -99,6 +100,7 @@ func newPackageCmd(out io.Writer) *cobra.Command {
 	f.StringVar(&pkg.keyring, "keyring", defaultKeyring(), "location of a public keyring")
 	f.StringVar(&pkg.version, "version", "", "set the version on the chart to this semver version")
 	f.StringVarP(&pkg.destination, "destination", "d", ".", "location to write the chart.")
+	f.BoolVarP(&pkg.dependencyUpdate, "dependency-update", "u", false, `update dependencies from "requirements.yaml" to dir "charts/" before packaging`)
 
 	return cmd
 }
@@ -109,6 +111,21 @@ func (p *packageCmd) run(cmd *cobra.Command, args []string) error {
 		return err
 	}
 
+	if p.dependencyUpdate {
+		dependencyUpdateCommand := &dependencyUpdateCmd{
+			out:      p.out,
+			keyring:  p.keyring,
+			helmhome: settings.Home,
+		}
+		dependencyUpdateCommand.chartpath, err = filepath.Abs(path)
+		if err != nil {
+			return err
+		}
+		if err := dependencyUpdateCommand.run(); err != nil {
+			return err
+		}
+	}
+
 	ch, err := chartutil.LoadDir(path)
 	if err != nil {
 		return err