Upgrade jshint to 2.x, centralize a whole bunch of global declarations for less hassle

Note that if you wish to test this by hand, you'll need to run "npm update" so that your node_modules directory picks up the change made to package.json.

Note that the default version it lints against is now ECMAScript 5.  From the blog post:

"JSHint will assume ES5 as the default environment. Before, JSHint was checking all the code per ES3 specification with an option to enable ES5 mode. Now ES5 mode is the default mode and if you want to check your code against the ES3 specification (useful when developing for super old browsers such as Internet Explorer 6) you will have to use es3:true."