Low level FUSE implementation

Just in case if you are interested, I just added the low level interface of FUSE to your project. It allows to work at inode level which might be useful sometimes.

If you want to use low level FUSE, you want to call f4js.llstart() instead of calling f4js.start().

There is an example of Low Level FS in example/ll_jsonFS.js which requires 1.json which is the root inode.