Fix issues with littlebits integration:

- Don't call create_dwolla_payment in after_filter
- Rename payment_method to dwolla_payment_method so we don't pollute
  the spree core checkout_controller.
- Destroy the non-dwolla payment that seems to get created with each
  checkout, then reload @order.payments
Merge branch '2-0-stable' into littlebits_integration
bump version
merge changes from 2-0-stable
resolve conflicts
add debugging around dwollacontroller's update and bump version
Move provider and payment_method to private (not actions)
Use custom debug_aware logging method
Checkout for payment source_type against string, not class constant
Merge pull request #5 from littlebitselectronics/fix_souce_type

Fix source type, make non-controller action methods private, use conditional logging method
bump version
use popup for oauth dialog
bump version; update readme