Finish analytics

[robredpath]

....whatever that means!

[Bjwebb]

This is basically finishing off https://github.com/TalkAboutLocal/local-news-engine/issues/16

[Bjwebb]

There's now a pull request for most of my work so far https://github.com/TalkAboutLocal/local-news-engine/pull/26

Remaining tasks:

• [x] Set up custom dimensions
• [x] Disable heartbeat timer
• [x] Record the date the page was generated
• [x] Track events when people open modals/expand records
• [x] Discuss whether this does what we need
• [x] Revert user tracking commit, we won't use this
• [x] Discuss content tracking https://github.com/TalkAboutLocal/local-news-engine/pull/58
• [x] Also set up analytics for areas.html https://github.com/TalkAboutLocal/local-news-engine/issues/57

[Bjwebb]

There's now a description of these changes in the pull request https://github.com/TalkAboutLocal/local-news-engine/pull/26