Feature/ Async storage + Google Drive example

this changes the storage class to work with Async storage providers,
and implements dos providers:
  - LocalStorage
  - Google Drive.
1) Agree on separate files. We could have a `conf.d` directory, and concat config.js and conf.d/* files before parsing, as seems to be the standard for many projects. Do you think we can leave that for a future ticket?

2) Right. I added same comments on the config file to explain that.