Add storage and cache wrappers to jail a storage to a subfolder
Add storage and cache wrappers to apply a permissions mask to a storage
Drop the readonly cache and wrapper in favour of the generic permissions mask wrappers
Replace the shared storage with the jail and permissions mask wrappers
Extract shared mount setup code to its own class
Use the post_initMountPoints hook instead of the setup hook
Add owner information to the result of the cache
Fix unit test