Pass `skip_token` config option to SimpleCov
* defaults to 'nocov'
Scope TestReporter configuration when setting 'skip_token' in SimpleCov
Use source_files to show covered_percent accurately

SimpleCov's HTMLFormatter uses source_files when displaying covered percent and this should do the same. This respects the nocov options.
Merge pull request #50 from codeclimate/nocov-skip_token

Support 'skip_token' option