Fixing a memory leak.

[ncochard]

Hello

With this pull request I am fixing the memory leak described in issue 104.

Firstly I had to change the package matchmedia to expose the dispose method so we can remove all listeners attached to the DOM. The author of matchmedia accepted my pull request but he never published the new version of matchmedia to the npm repository. So I published the corrected package under a different name matchmediaquery.

In this pull request:

1. I make use of matchmediaquery rather than matchmedia.
2. I call the dispose method to ensure that all listeners are removed.
3. And I also make use of the utility cross-env so that this package can be compiled on windows.

I hope it all makes sense and that this pull request can be consumed. I've tested it in our project and it works well. If you have any question or comments, feel free to ask.

Regards

[yocontra]

Thanks for doing the work on this one!

[ncochard]

Thank you very much. Much appreciated.
When you have a moment, would you mind running the following commands?

npm run build
npm publish

Thank you :-)