Log Message:
Update ruby-minitest to 5.8.3.

=== 5.8.3 / 2015-11-17

* 1 minor enhancement:

  * Added extra note about mocks and threads to readme. (zamith)

* 1 bug fix:

  * Fixed bug in Mock#verify. (pithub/zamith)

=== 5.8.2 / 2015-10-26

* 1 bug fix:

  * Fixed using parallelize_me! and capture_io (or any locking io). (arlt/tenderlove)