Added four Angular JS libraries

Added four AngularJS libraries - [angular-charts](http://chinmaymk.github.io/angular-charts/), [angular-dragdrop](http://codef0rmer.github.io/angular-dragdrop), [angular-file-upload](https://github.com/nervgh/angular-file-upload), [angular-google-maps](http://angular-google-maps.org)