Update bonobos spree branch

Was causing some spec failures.
Add WebhookController.error_notifier attribute

To allow applications to report errors to their error reporting tools.

Changes:

1. Added a "WebhookController.error_notifier" class attribute and the code to call it
2. Updated Responder to store exception objects so they can be forwarded
3. Updated responder.backtrace to responder.exception.backtrace
4. Updated WebhookController to actually use ResponderSerializer

Conflicts:
	README.md
	app/controllers/spree/wombat/webhook_controller.rb
	lib/spree/wombat/handler/base.rb

cherry-picked from c6f2dd8bbc845b9fb8d7b27f610f4cfdf57b52d6 in spree/spree_wombat/master

Fixes #31
Remove honeybadger dependency

Now that we have the WebhookController.error_notifier hook.