Add Google Analytics

[nathan-hekman]

Very important

Use Google Analytics, see ICT codebase for some shortcuts.

• Send events when user minimizes app (AppDelegate methods)
• want to be able to describe average session of a user, and how many of them are there (users). average session lengths and how many users.
• average number of things in stream, average number of people in stream
• average content length
• capture count of every major button click
• steambot data (when added)

Verify with Nathan.

[glennrfisher]

Created #203 to track the subtasks.