Add stats tracking events to user actions

[mitchdowney]

Prior to adding tracking events, display a modal after a user logs in for the first time, that asks them for permission to track their stats.

Stats should be tracked for:

• account
• channel
• clip
• item
• playlist

The stats events should only fire for logged in users with active premium memberships.

account: on page visit

channel: on page visit, play item, clip, chapter, or soundbite

clip: on page visit, or play clip

item: on page visit, play item, clip, chapter, or soundbite

playlist: on page visit