Give the user more feedback upon a successful |boot2docker init|

Previously there was zero output to the console if init completed
successfully, which gave the impression that nothing had occurred. Now
we explain that the VM has been initialized, as well as how to start it.

Author: Ed Morley

cmds.go

@@ -66,6 +66,8 @@ func cmdInit() error {
 	if err != nil {
 		return fmt.Errorf("Failed to initialize machine %q: %s", B2D.VM, err)
 	}
+	fmt.Printf("Initialization of virtual machine %q complete.\n", B2D.VM)
+	fmt.Printf("Use `boot2docker up` to start it.\n")
 	return nil
 }