Use Minitest::StatisticsReporter

Minitest::StatisticsReporter#report already gathers the statistics, so
we can delegate stat-gathering to it and just call our notifier with the
stats.
--pride option not available in minitest < 5.0
fix specs
Merge pull request #66 from sbl/pride_bug

Don't use the --pride option for Minitest < 5.0
Update the changelog
Merge pull request #65 from kejadlen/feature/minitest-reporter

Use `Minitest::StatisticsReporter` instead of `Minitest::Reporter` for Minitest > 5.0
Update Changelog and Contribution guide

[ci skip]
Bump to 1.0.0.rc.1
Fix spec
Drop the `--pride` option.

Users should add `require 'minitest/pride'` to their `test_helper.rb`
instead.
Ensure `Minitest::Reporter` is used for Minitest < 5.0.4 (precisely)
Update Changelog
Bump to 1.0.0.rc.2
Merge remote-tracking branch 'upstream/master'