Bump strip-ansi dep to 1.x

In the near future, `^0.x.y` will only allow exactly the `0.x.y` version, in
accordance with the specification at http://semver.org

The `strip-ansi` package has recently updated to 1.0.0, with no significant
API change, so we should be using that instead now.
Merge pull request #10 from isaacs/patch-1

Bump strip-ansi dep to 1.x