Migrating to Version 2.0.0

Please note the following changes, when you migrate from a version below 2.0.0:

• The options object changed and requires using a personal access token. See here.
• The callback structure changed. I decided to apply a node convention called Error-First in which a callback function's first parameter is the error. See here.

Before opening an issue, please confirm that you changed your code according to these changes.