Enhancement for file uploader and file manager

[woodpig07]

Refer to https://github.com/Wiredcraft/jekyllpro/issues/33

• Implemented list view and icon view for file manager
• If in the schema file it has ui:options to specify the default upload folder, then set to that path when opening the file uploader.

  "uiSchema": {
  "body": {
    "ui:widget": "customCodeMirror",
    "ui:help": "Description of the product",
    "ui:options": {
      "file_dir": "images/products"
    }
  },