Added belongs_to :user to give it access to user
Added 'customer_token' method
Added comment about @user.customer_token
Related user to payment and added amount and reference_id
Changed syntax for StripeEvent
Added comments
Tested: 'returns the customer token for a valid card'
Added more specs
Added ngrok to this app's root directory
Removed payment_spec.rb
Added cassettes when running rspec
Used redis-server