Split big acceptance tests into multiple tests

In addition, add some test variables and helper methods.
Make finer-grained example tests
Improve readability of the specs with an intermediate class
Assert that stdout/err are empty
Rewrite Minitest reporter for 5.0 compatibility
Reenable pending test
Remove tests that don't provide much value over other tests
Minitest or RSpec? :P
Merge pull request #4 from ci-reporter/minitest-5

Minitest 5