* - wanCache : WANObjectCache object to use for persistent caching.
* - mimeCallback : Callback that takes (storage path, content, file system path) and
* returns the MIME type of the file or 'unknown/unknown'. The file
* - wanCache : WANObjectCache object to use for persistent caching.
* - mimeCallback : Callback that takes (storage path, content, file system path) and
* returns the MIME type of the file or 'unknown/unknown'. The file