Updated {,dev}dependences to use the latest “minor” version

My reasoning is that the semver form `~1.1.x` is (although still useful) relatively narrow.  There have been many updates to Stylus, Nib, and CoffeeScript, but since the plugin used the `~` form for dependencies, npm never grabbed any of the newer versions.  

Since semver is so widespread, I think it’s safe to just stick to a major version.  Future minor versions will add benefit without breaking anything (since semver states that any backward-incompatible change must increment the major version number).