Initial commit that can call the Sonar API and display a tabular view of metrics
Aggregate metrics over the last year instead of summarising the current metrics

Currently only displays as a data table, next up is adding some trends
Added morris.js trends for Sonar metrics to the dashboard
Refactored trends directive to use a HTML template and tidied up index page
Moved DashboardCtrl to SonarCtrl to make way for other types of metrics (e.g. Gerrit)
Added goals and units to Sonar trends