Doesn't compile with Rust 1.0.0 (stable)

[Diti]

Wanting to see a demo of your lib, I tried to run a binary first:

$ cargo run
    Updating registry `https://github.com/rust-lang/crates.io-index`
 Downloading libc v0.1.8
 Downloading num v0.1.24
   Compiling libc v0.1.8
   Compiling rustc-serialize v0.3.14
   Compiling rand v0.3.8
   Compiling num v0.1.24
   Compiling qrcode v0.1.5 (file:///private/tmp/qrcode-rust)
     Running `target/debug/qrencode`
thread '<main>' panicked at 'called `Option::unwrap()` on a `None` value', /private/tmp/rust20150518-25853-gds1ok/rustc-1.0.0/src/libcore/option.rs:362
An unknown error occurred

Seeing that your code doesn't compile even though it passes your Travis CI tests, I ran the tests myself:

$ cargo test
   Compiling qrcode v0.1.5 (file:///private/tmp/qrcode-rust)
src/lib.rs:21:19: 21:33 error: unstable feature
src/lib.rs:21 #![cfg_attr(test, feature(test))] // Unstable libraries
                                ^~~~~~~~~~~~~~
note: this feature may not be used in the stable release channel
error: aborting due to previous error
Could not compile `qrcode`.

Since Rust 1.0 is out of beta, your code will not compile on Rust stable versions, only nightlies. See Stability as a Deliverable.