Update tracking

[abridger]

• Rename analytics module to tracking in line with other Kano properties
• Add tracking methods to allow for custom variables and fuller virtualPageViews
• Update existing analytics.track methods to use new tracking.dispatchTrackingEvent method and update event naming in line with new requirements
• Remove analytics/tracking imports where not needed
• Add new twitterShare method to allow for Twitter shares to be tracked
• Add originalLocation in the index to fix faulty GTM referrals

Trello cards: https://trello.com/c/H9GQzD5i/1631-1-prevent-gtm-rogue-referral-issue https://trello.com/c/rjMJSqys/1621-2-implement-kano-code-tracking-on-make-art