This File adapter provides basic support for `write`, `read`, `delete`
and `clear` cache functionality, as well as allowing the first four
methods to be filtered as per the Lithium filtering system. The File adapter
is a very simple cache, and should only be used for prototyping or for specifically
caching _files_. For more general caching needs, please consider using a more
appropriate cache adapter.

This adapter does *not* provide increment/decrement functionality. For such
functionality, please use a more appropriate cache adapter.

This adapter does *not* allow multi-key operations for any methods.

The path that the cached files will be written to defaults to
`<app>/resources/tmp/cache`, but is user-configurable on cache configuration.

Note that the cache expiration time is stored within the first few bytes
of the cached data, and is transparently added and/or removed when values
are stored and/or retrieved from the cache.