2.1.0

• New Feature: Add support for object expansion - #393
  • credits to [@swelham](https://github.com/swelham
  • see instructions in README.md
• Replace user_id in event with account field, as per updated stripe documentation - #391
  • credits to @erikreedstrom
• Update officiall supported API version to 2018-05-21 - [#390]((#390)
  • credits to @snewcomer