Add packaging for Meteor.js, http://meteor.com

Hi Craig,

I'm a Meteor.js dev and volunteer package maintainer for [Meteor](http://meteor.com). We have a few wrapper packages for Mousetrap that were getting out of sync, and thought it'd be best if the integration comes straight from the source - hence this PR.

This PR will let you directly publish updated versions of the library as they become available. All you have to do is create an account at https://meteor.com/ (click *SIGN IN*, then *Create account*). After you've done that, please let me know the name of the account, and I'll add you as a maintainer.

I've already published the current version of the package on [Atmosphere](https://atmospherejs.com/mousetrap/mousetrap) (Meteor's package directory). When you release new versions, you'll be able to publish them to Atmosphere by running `meteor/publish.sh`.

Thanks & best regards,
Dan, [official Meteor integrations team](https://github.com/raix/Meteor-community-discussions/issues/14)