Pass user-generated Stripe exceptions through

This ensures that when StripeError is generated during the subscribed
block, the exception is passed through to layers past StripeEvent
rather than caught and returning a 401. Mostly useful during development
to let developers see their exceptions.

Re issue #23
Merge pull request #26 from adamonduty/user_exceptions

Pass user-generated Stripe exceptions through
Provide additional information about Stripe exceptions
Add adapter object to wrap subscriber blocks
Cleanup controller specs
Remove core ext for set in specs
Update author email
Adjust dependencies to make rails optional
Update test gemfiles
Prefer new hash syntax
Refactor test suite
Subscribe to all event types with StripeEvent.all
Refactor event dispatch to use internal namespace

Hooray, we no longer need to maintain a list of event types!
Subscribers can be any object which responds to #call
Update Stripe dashboard image
Add testing section to readme
Add example of custom event retriever
Update ruby versions to run against in CI
Typo fix
Bump version to 1.0.0.rc