Full refactor

- Use Coffeescript instead of Ruby (+ Opal javascript conversion)
- Add a change log
- Add a Travis CI file to build and test the module
- Update module dependencies
- Enrich the package.json
Yes, the ```?``` indeed does what you say. But the official plus dont use it there. I kind of thought the presence of ```@editor``` is guaranteed for a ```Provider```.

I never saw it failing myself, but if you prefer, I'd be glad to add it again.

See:
* https://github.com/saschagehlich/autocomplete-plus/blob/master/lib/fuzzy-provider.coffee#L28
* https://github.com/saschagehlich/autocomplete-paths/blob/master/lib/paths-provider.coffee#L13
* https://github.com/saschagehlich/autocomplete-snippets/blob/master/lib/snippets-provider.coffee#L27