modifies links to match the public URL paths that should be exposed to
clients, using configured ResourceResolver strategies
appends a comment in the manifest, containing a Hash
(e.g. "# Hash: 9de0f09ed7caf84e885f1f0f11c7e326"), thus changing the content
of the manifest in order to trigger an appcache reload in the browser.
All files with an ".appcache" file extension (or the extension given
to the constructor) will be transformed by this class. The hash is computed
using the content of the appcache manifest so that changes in the manifest
should invalidate the browser cache. This should also work with changes in
referenced resources whose links are also versioned.