Update to notty v0.2.2 upsteam

[OlivierBlanvillain]

Before this patch, I'm getting the following compilation error:

File "vendor/notty-0/lwt/notty_lwt.ml", line 68, characters 25-64:  
Error: This expression has type (unit -> unit) Lwt.t                 
       but an expression was expected of type unit Lwt.t
Hint: Did you forget to provide `()' as argument?   

Everything seams to compile with the latest netty release.

[alexozer]

Fixed in 666c548.