Add queries on hoa://Test/Vfs/.

Example:
  * `hoa://Test/Vfs/Foo.bar?mtime=42&permissions=0644` returns pathname to a file with a mtime sets to 42 and permissions set to 0644.

So far `atime`, `ctime`, `mtime` and `permissions` are supported.

Thoughts? /cc @jubianchi and @mageekguy especially 'cause I am sure you will like that ;-).