language: rust
matrix:
  include:
    - rust: 1.6.0
    - rust: stable
    - rust: stable
      os: osx
    - rust: beta
    - rust: nightly
script:
  - cargo test

language: rust
matrix:
  include:
    - rust: 1.13.0
    - rust: stable
    - rust: stable
      os: osx
    - rust: beta
    - rust: nightly
script:
  - cargo test

Change Rust 1.6.0 to 1.13.0
[Travis] Change Rust 1.6.0 to 1.13.0

The 'unused_unsafe' attribute was stabilized in 1.13.0.
