* Add matrix-analytics-events as a dependency
* Make IEvent look like a stub definition
* Update pageview tracking to track screens, using a hypothetical definition of a screen event
* Remove distinction between pseudo and anon tracking, will need to rework it considering stubs
Piwik supports sending an event value, which we can use to indicate
cardinality of UISIs to be tracked instead of tracking them individually.
This means we can track them at a lower frequency of (fairly arbitrary)
60s.
Instead of pinging Analytics once per failed decryption, add the failure
to a list of failures and after a grace period, add it to a FIFO for
tracking. On an interval, track a single failure from the FIFO.
