Fixed build for irsc

Hey, I fixed the travis build for the current irsc making it work with rust nightly (24/12/2014).

Its been a nice quiet christmas afternoon here so I thought, why not play with Rust and try and build an IRC bot? Figured I'd fix your library in the process.

I haven't really improved anything, just updated the syntax where required to make it compile. I had to unwrap the results from the regex matches which now come inside Option structs and cast the function pointers when registering event handlers for the callback.
This is good, but not optimal. Would you change `.into_string()` into `.to_owned()`, as `.into_string()` is deprecated now?