Port README to Markdown, so that it shows up on npmjs.org

Also, address a 'jshint' issue with how nulls are compared. 

Thanks for porting my favorite Perl paging library to JavaScript.

I have some interest in potentially forking to be a more natural node.js package including:

- Using camel case instead of "snake case"-- I prefer Perl casing style in insulation but camelCase is unfortunately important for being a good cultural fit for npm modules
- Using "module.exports" to export code from the module.