Change `to_str()` -> `to_string()` where necessary

* Alters several outdated uses of `to_str()`
* `Message::to_str()` renamed so `Message` continues to impl. `Show`
Update examples w/ change of `to_str()`
Merge pull request #40 from drbawb/feature/to-str-rename

`ToStr` renamed to `ToString`
update to head, switch to cargo
shift over to cargo to build everything
Update to rust HEAD
Add Message::as_bytes
Add Message::as_str
breaking change: tweaks to poll and PollItem

* PollItem should take lifetime to make sure it doesn't outlive a socket
* PollItem.revents should be private and turned into a method
* `poll` should return an `int` as it's the number of signaled events.
Updated to use .to_vec instead of .to_owned.
to_owned() -> to_vec()
Use std::time::Duration
Merge pull request #43 from jedisct1/master

Minor fixes for rust-nightly
Merge pull request #41 from reem/to-vec

Updated to use .to_vec instead of .to_owned.
fix a cargo warning
update travis config
Ignore the Cargo.lock file
static -> const
str::raw::from_c_str() -> std::string::raw::from_buf()
fail!() -> panic!()