update unit test to account for the fact that we changed the query param for specifying the model id.

report the users name as "You" when it's an activity they did themselves, and simplify a couple other things with activity description rendering.

get colors and a couple more things working with activity user initials, fix up formatting for database-sync type activity.

when recording a database-sync activity set the database_id value as well as the model_id value for the activity.

do a little cleanup work on our event processors to make them more robust and fix a small bug in the event tracking for database sync.

adding in the new view tracking code so that we can have an accurate Recents section on the homepage (implements #938)

cleanup the way the ActivityDescription is rendered and use a small react component to wrap that display.

get all of the card filtering by Table stuff working.  formatting is pretty close now on Saved Questions tab.

do a quick reshuffling of the events lifecycle functions so that we can make it easy to spin up new event listeners for different things, including our second listener which will be for view count tracking.

finish off card activity handling by adding in ability to track the database & table associated with an activity item.

be consistent about using :custom_id instead of :tracking-hash or other ways of specifying an activity custom identifier.

update the database sync event publication so that we can actually track start & end as separate events but part of the same activity.  to do so we add a :tracking-hash to the events when they are published which is meant to remain consistent throughout the sync, then we implement our activity tracking code so that we can lookup an existing activity item and update it based on the custom hash.

publish and :install event and listen for it in our activity feed so that we can create the first entry.  also, implement user login event handling so that we can identify when a user logs in for the first time and we can publish an activity feed entry for :user-joined.

streamlining more of the event bus and activity stuff and rounding things out.  adding new migration which creates the `activity` table.

rounding out a few things.  now have all persistent functions for cards & dashboards publishing activity events.

kill unused deps. fixes #947