Add JSDoc to codebase

[ryanone]

Per our team meeting, I'd like to task out different people to apply JSDoc to files throughout the codebase:

• @asakusuma
  • lib/coverage - CliReporter.js
  • lib/uac - casper.js, phantom.js, selenium.js
• @sethmcl
  • lib/util - commentsParser.js, fsHelper.js, i18n.js, locale.js, logger.js
• @ryanone
  • lib/util - pathHelper.js, stringUtil.js
  • lib - config.js, coverage.js, executor.js, testcase.js, testrun.js

Make all check-ins against this issue. We can do locales/ and test/ after this wave of files. I didn't include @roelrz since he's enjoying sandy beaches and the clear, blue ocean. We can loop him in when he gets back.

We're using JSDoc3 to generate docs. If you're wondering how to create JSDoc, just look here and/or at Venus.js for examples.

Thoughts?