Support minitest >= 4.7

resolve #7
Support minitest5's verbose output
Reject minitest5's empty test methods
Fix incorrectly triggered TestQueue::Iterator#each
runner/minitest.rb requires correct runner
Merge remote-tracking branch 'origin/master' into minitest5
rename samples
add tests for minitest5
work around minitest_reporter_plugin trying to read iterator
some docs
Start developing to support rspec 3.0
Separate RSpec::Core::QueueRunner
Bump supporting rspec version

Now supports rspec >= 2.13