Update blueprint custom-post to use literal:directory i

[bph]

The current relevat steps:

{
	"step": "mkdir",
	"path": "/wordpress/wp-content/plugins/books"
		},
		{
			"step": "writeFile",
			"path": "/wordpress/wp-content/plugins/books/books.php",
			"data": {
				"resource": "url",
				"url": "https://raw.githubusercontent.com/wordpress/blueprints/trunk/blueprints/custom-post/books.php"
			}
		},

Become something like this:

{
  "step": "installPlugin",
  "pluginData": {
    "resource": "literal:directory",
    "name": "books",
    "files": {
      "books.php": {
        "resource": "url",
        "url": "https://raw.githubusercontent.com/wordpress/blueprints/trunk/blueprints/custom-post/books.php"
      }
    }
  },
  "options": {
    "activate": true
  }
}

That actually assumes that installPlugin step handles both creating the directory and writing the file in one go.

If that assumption is wrong, here is the alternative:

{
  "step": "writeFiles",
  "writeToPath": "/wordpress/wp-content/plugins/books",
  "filesTree": {
    "name": "books",
    "files": {
      "books.php": {
        "resource": "url",
        "url": "https://raw.githubusercontent.com/wordpress/blueprints/trunk/blueprints/custom-post/books.php"
      }
    }
  }
},
{
  "step": "activatePlugin",
  "pluginPath": "books/books.php"
}

@adamziel @brandonpayton any thoughts here?