Two commits : Add action on click and Add 3 others Features

## Onclick action
Example : http://jsfiddle.net/CDLXE/5/ // Click on blue part

## Add three Features
* Relative font-size : permit to avoid summaryTitle or summaryNumber exceeds the donut.
* Label in the donut : like tip, but title is set in the summaryTitle `<p />` .
* Number shortener : e. g. to print 200K rather than 200000 (or 200M rather than 200000000).

Example for the first two features : http://jsfiddle.net/CDLXE/6/
Example for the last one : http://jsfiddle.net/CDLXE/7/