Add task to remove console.log (see #1147 & #1243)

Added a new Grunt task to the build process to remove `console.log` statements. This is important for production since, in some versions of IE, the `console` object is only created after opening the Dev Tools.

Other calls like `console.warn` are kept since they may be useful in production. An e.g. from the source:

```javascript
console.warn("You need to include froogaloop for vimeo to work");
```

This doesn't update the `build` dir because files were already different when I ran `grunt` on the master. But I can add that if you want. Thanks for this great project :+1: