Log Message:
Update ruby-simplecov to 0.12.0.

0.12.0 2016-07-02 \ 
([changes](https://github.com/colszowka/simplecov/compare/v0.11.2...v0.12.0))
=================

## Enhancements

* Add support for JSON versions 2.x

## Bugfixes

* Fix coverage rate of the parallel_tests. See \ 
[#441](https://github.com/colszowka/simplecov/pull/441) (thanks @sinsoku)
* Fix a regression on old rubies that failed to work with the recently \ 
introduced frozen VERSION string. See \ 
[#461](https://github.com/colszowka/simplecov/pull/461) (thanks @leafle)