Can't properly send data through Write.

[nyovaya]

On the client I sent data through SctpStream's Write impl.
On the server side I tried to read it using:

let sock = sctp::SctpEndpoint::bind("127.0.0.1:2000").unwrap();
loop{
let mut v = Vec::new();
sock.recv_from(&mut v[..]).unwrap();
println!("msg: {}", std::str::from_utf8(&v[..]).unwrap());
}

This returns the error:

thread 'main' panicked at 'called Result::unwrap() on an Err value: Os { code: 0, kind: Other, message: "Success" }', libcore/result.rs:1009:5

[nyovaya]

Ok it was because the slice's size is 0 - I don't like the Error message, it should return a proper error message when the len is 0.

[nyovaya]

I would create a PR - @phsym still working on this one? - I have others additions too.