Use a more specific match for changing to worker

httpd from centos.alt.ru has both #HTTPD=/usr/sbin/httpd.worker and
confused
Add Serverspec matchers
Disable selinux first
Add system tests for prefork / worker mpm module
Correct cgi/cgid loading on worker/prefork
Merge pull request #263 from hunner/worker_multiple_matches

Use a more specific match for changing worker/prefork
Release 0.8.1

Bugfixes:
- Update `apache::mpm_module` detection for worker/prefork
- Update `apache::mod::cgi` and `apache::mod::cgid` detection for
  worker/prefork
Merge pull request #269 from hunner/release_0.8.1

Release 0.8.1