Support a Given/When/Then declaration syntax

[greghaskins]

A feature request from @ashleyfrieze. It would be cool to be able to declare specs with a syntax similar to Cucumber.

This could either be a Spectrum add-on like rspec-given is for RSpec or the beginnings of multiple interfaces like in Mocha.

[ashleyfrieze]

The end-game of this for me is:

• Make it easy to use Feature/Scenario/Given/When/Then/And to structure specs
  • Note: this means that the lowest unit of this Gherkin-style spec is actually a step, not an independent spec as it is with the describe/it syntax
• Treat the execution of Given/When/Then/And as a single spec, so any failure will apply to all steps within the parent
• Allow for the sharing of test execution state between steps - this is pretty much essential, since the Then step is usually asserting the outcome of executing a Then step - so it needs to be able to probe the result of Then
• Optional: it might be nice to be able to output pure Gherkin from Spectrum. In fact, it might be nice to be able to render Spectrum in more than just the JUnit runner UI and surefire/failsafe/etc reports.

[ashleyfrieze]

Now you've merged #51 does this close?

[greghaskins]

Closed by #51.