Add noninteraction parameter for ga.js event tracking

* The ga.js version of track event supports an optional boolean parameter called 'noninteraction' that is provided for determining if the event is considered counted as an interaction for bounce rate. By default this
value is false, as per the ga.js spec, which infers the event is counted as an interaction.
* Added missing method headers for _trackEvent and _trackPage.
* All of the spacing in the readme is now consistent with the rest of the project.
* A little tuning to enable curly bracket checking all the time and remove obsolete comments.
* Added proper spacing after commas where it was missing.