Add Windows support and enable CI

.cargo/config

.travis.yml

.travis/redox-toolchain.sh

Cargo.toml

appveyor.yml

ci/before_deploy.ps1

ci/before_deploy.sh

ci/install.sh

ci/script.sh

src/lib.rs

src/platform/mod.rs

src/platform/windows.rs

src/redox.rs

src/unix.rs

src/windows.rs