Improved code quality

Hi Ben,

I propose this merge to you : 

- added jshint grunt task
- .jshintrc
- fixed lint error
- build/default d3pie

I use WebStorm as IDE and i can link .jshintrc file to my JSHINT setting. The IDE code editor is then synchronized with the project code quality params.
Now, each grunt alias will run JSHINT first.


thx

need indent