Add a Bitdeli badge to README

Author: bitdeli-chef

README.md

@@ -262,3 +262,7 @@ For transparency into our release cycle and in striving to maintain backward com
 
 ### Copyright and license
 Code and documentation released under [the MIT license](https://github.com/joni2back/angular-filemanager/blob/master/LICENSE). 
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+[![Bitdeli Badge](https://d2weczhvl823v0.cloudfront.net/joni2back/angular-filemanager/trend.png)](https://bitdeli.com/free "Bitdeli Badge")
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