Improved Top-4 Metrics

We've changed the top 4 metrics that we show in both the dashboard and when viewing a single Journey, they are now:

* Journey Opens - how many times were your Journeys (or a single Journey opened)

* Steps Viewed - how many times were steps within Journeys (or a single Journey) viewed

* Emails Captured - how many emails were captured (across all Journeys or a specific Journey)

* Content Interactions - how many times was content within steps interacted with, for example videos played, calendars booked, PDF pages changed, etc.

Thanks to Oytun for shipping this!