Add a few dev features.

Hey @vladikoff,

I was in the process of looking at the code for gruntjs.com since I'll be adding the page for the mini-badge.

I added a few dev features that I think are helpful for development and team collaboration: 

- `.jshintrc` so you can lint your code on save with a linter plugin for your editor.
- `.editorconfig` that mirror the settings used in this project.
- `grunt-open` and `grunt-concurrent` to open up the local server in your default browser when you type `grunt serve` in the cli.
- `load-grunt-tasks` module so we don't have to call the `loadNPMTasks` function after installing a new grunt tasks.

What do you think?

- Kahlil