Enable curly checking for jshint

* A little tuning to enable curly bracket checking all the time and remove
obsolete comments.
* Added proper spacing after commas where it was missing.
Spacing fixes in readme

All of the spacing in the readme is now consistent with the rest of the
project.
Add noninteraction parameter to ga.js event tracking

* The older version of track event has 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.
* Also added missing method headers for _trackEvent and _trackPage.
Standardized ga.js and analytics.js check calls

* There was a lot of if (ga.js) { ... } else if (analytics.js) { }
statements throughout the code, but they weren't always consistent in
how they were defined. Replaced this with a callback style function call
to check and then execute if the appropriate script is loaded.
* Added a few more tests for trackEvent to test the non-interaction
parameter
* Improved trackPage and trackEvent tests to validate the ga construct
states.
Merge pull request #51 from justinsa/master

Add noninteraction parameter for ga.js event tracking