Glob support

Allow to specify glob file patterns on the command line and in package.json scripts.

With this patch, I can put a "lint" script into my package.json that does `"jslint ./**/*.js"` to lint all files in my project and it works the same way on Linux, Mac and Windows. It also ignores paths that start with `node_modules`.

Note that I've updated the instructions for "JSLint your entire project" in the README.md and added a test case.
Please let me know if there is anything to improve.