kite/klient: extend "fs.*" methods

[acbodine]

Required for Koding UI to draw file tree and execute actions like "perm" change and so on (but given the read-only nature of containers, it's discussible whether UI should allow for it)

[acbodine]

Start by validating that the existing fs.* kite handlers work inside the klient container. Then figure out what to do about other containers in the stack.