Remove jshint pragmas, add global config - still passing

There might be an issue for developers who have jshint on by default in their editor (see [this commit](https://github.com/sejoker/jschat/commit/7771bc2a6d91ff5296e8c338feafb62285f1b835) for example), and since there's no hard rules laid out in the project, we can add global variables & ability to pass on 'use strict' for now.