metrics

based on #34 & #10 

Provide metrics, based on  http://jenkins-php.org/, replacing `phpdox` with `phpdoc2`.

The end result would mean user can view metrics at:
 - `http://localhost/metrics/plugins/$plugin/`
 - `http://localhost/metrics/plugins/$plugin/logs/`
 - `http://localhost/metrics/themes/$plugin/`
 - `http://localhost/metrics/themes/$plugin/logs/`