Drop support for Rspec 2
Actually work with rspec 3.0.3

This changes the reopening of ProgressFormatter so that it doesn't give
an error; example_passed was not available as super. (and other changes)

The definition of the generative test method is also changed, so that it
works. This lost some coloring on the name maybe.
Use super instead of setup_ivars for Rake task
Update formatters for RSpec 3
Fix acceptance tests, better error messages
Bump version to 0.2.0.pre3
Bump version to 0.2.0