Add issues by developer and issues by status metrics.

The 3 metrics (by developer, by status and by priority) are DISTRIB metrics.
Updated the widget to show issues by status & priority. A separate widget shows the issues by developper.
Merge branch 'moremetrics' of https://github.com/Typz/sonar-redmine into Typz-moremetrics
Merge pull request #10 from SonarCommunity/Typz-moremetrics

Typz moremetrics