RFC: add an instantReplay feature (built-in data mocking)

[garris]

Sometimes when working with dynamic content, hiding and deleting selectors isn't enough. If we really want to test our CSS changes proper we need to use the same DOM data. Unfortunately -- it's not always easy to mock data -- especially if we are testing a production site...

I would like to propose that the gulp reference flow also capture actual DOM selector data and (as an option) re-injected that data when running gulp test

Comments welcome!

see implementation ideas in the "instantReplay" branch