Upgraded package dependencies

Fixed breaking changes in googleapis:

- Callback signature changed from f(err, body, res) to f(err, res)
  where body has moved to res->data.
  https://github.com/google/google-api-nodejs-client/releases/tag/v25.0.0

- The library now requries the use of ES6 named imports.
  https://github.com/google/google-api-nodejs-client/releases/tag/v26.0.0

getVariables - A convenience method to fetch multiple variables

Version 0.2.0

Added usage example (v0.1.1)

Version bump, 0.1.0