added bitdeli badge.

Author: Chris Maurer

README.md

@@ -8,6 +8,7 @@
 [![Dependencies Status](https://david-dm.org/cmaurer/angularjs-nvd3-directives.png)](https://david-dm.org/cmaurer/angularjs-nvd3-directives#info=dependencies)
 [![devDependency Status](https://david-dm.org/alanshaw/david-www/dev-status.png)](https://david-dm.org/cmaurer/angularjs-nvd3-directives#info=devDependencies)
 [![Coverage Status](https://coveralls.io/repos/cmaurer/angularjs-nvd3-directives/badge.png)](https://coveralls.io/r/cmaurer/angularjs-nvd3-directives)
+[![Bitdeli Badge](https://d2weczhvl823v0.cloudfront.net/cmaurer/angularjs-nvd3-directives/trend.png)](https://bitdeli.com/free "Bitdeli Badge")
 
 ![Line Charts](http://cmaurer.github.io/img/line.chart.png "Line Charts")