Update Package To Use New autocomplete-plus API

[joefitzgerald]

Please:

• Switch to the new autocomplete-plus 1.0.0 API: https://github.com/atom-community/autocomplete-plus/wiki/Provider-API
• Don't depend on autocomplete-plus in your package.json
• Move away from having 1 provider instance for every editor instance

[joefitzgerald]

The old API will be removed on Tuesday, February 10th, 2015. Please update to the new API, or let me know if you have issues with this timeline.