pay: Multiple errors and issues with Devise and Stripe

Hi there!

I’m following the “Using Stripe Elements and Devise” wiki entry but I’m facing a few issues.

1. Adding a pay initializer causes NoMethodError’s (e.g: NoMethodError: undefined method application_name=' for Pay:Module)
2. Stripe wasn’t picking up credentials until I’ve updated my Gemfile to fetch the gem directly from jasoncharnes/pay
3. Upon submit I’m faced with a Faraday::ClientError at /users the server responded with status 400 error.

Any ideas how to fix the last one? I do appreciate and love the work you guys put into this gem though! 😃