Make route-recognizer requireable in nodejs

While one can install route-recognizer in nodejs it is not possible to require it using require('route-recognizer'). This can be fixed by specifying a "main" file in ```package.json```.

While this makes route-recognizer requireable, it is still exported to ```module.exports.default``` which is weird because this forces me to use ```var RouteRecognizer = require('route-recognizer')['default']```. But since I don't understand the build system enough I can't fix that. (BTW the same applies to the AMD module)