Bumped version number to correlate with tag and http://semver.org/ conventions

This PR does two simple things:

As per the [Bower.io](http://bower.io) *registering packages* guidelines our repo needs to have proper git tags for each version we publish:
> Your package should use semver Git tags.

Therefore, I have setup the first tag [here](https://github.com/guardian/sass-mq/releases/tag/v1.0.0)

As per the [*semantic versioning*](http://semver.org/) guidelines if we're using the software in production then it should be at least v1.0.0:
>If your software is being used in production, it should probably already be 1.0.0. If you have a stable API on which users have come to depend, you should be 1.0.0. If you're worrying a lot about backwards compatibility, you should probably already be 1.0.0.