Added fiber-cucumber.js.

Originally taken from

https://github.com/mozilla/aestimia/blob/master/test/acceptance/fiber-cucumber.js
Added one scenario with step defn's set to pending.

Feature taken from:

https://github.com/mozilla/openbadges/wiki/Acceptance-Brainstorming
Implemented three basic scenarios
Scenario rewording/refactoring.
Added a multiple-badge issuing scenario.
moved support code into features/support/env.js.
rewrote feature description/background.
typo fix
Added a scenario for recipient/backpack email mismatch.
Refactored step definitions; moved issued badge tracking to support lib.
In step definitions, renamed 'sending' to 'sendGroup'.
Added fibrous.js with tests.

From the docs for fibrous:

// Return a wrapped 'fibrous' version of the given function that takes
// a callback as a MANDATORY final argument, and doesn't take a function
// as any of its other arguments.
//
// If the fibrous version is run in a Fiber and not given a callback,
// it will call its wrapped function with a Future, wait until the
// Future is resolved, and return the result (or throw an exception).
//
// If the fibrous version is not called in a Fiber, or is passed
// a callback, the wrapped function will be called with the same
// arguments.
Added initial send-to-backpack-request.js with tests.
Added SendToBackpackRequest.Group.
modified cucumber environment to match SendToBackpackRequest interface.
made the fake backpack in SendToBackpackRequest.Group an array.
Added a TODO to SendToBackpackRequest.Group.
Reorder SendToBackpackRequest arguments in env.js to match implementation
Made acceptance tests use real SendToBackpackRequest and
SendToBackpackRequest.Group objects. This involved upgrading
the acceptance test notion of badges to urls backed by actual
badgehost assertions, as well as enhancing the internal
FakeBackpack class.

Also added some more detailed assertions to a few step definitions.
Merge pull request #1 from stenington/cucumber

Acceptance tests now use our "real" SendToBackpackRequest and SendToBackpackRequest.Group implementations.