Upgrade to universal Google Analytics.  Report two custom session dimensions: signed in & locale.
Better report signin & user-chosen language in analytics.
Avoid possible crash when missing browser language.
Do more analytics logic in ruby than javascript.
Only report language analytic when we have a browser language to compare to.
Include analytics report in javascript tag.
Merge pull request #728 from code-dot-org/analytics

Upgrade to Universal Google Analytics.
Report user locale to a new dimension in GA when it differs from what their browser would want.. letting us see how many users are overriding the default language we would choose for them, either via cookie or user setting.