Alias user on create

[joshsmith]

What's in this PR?

Allows us to alias the user on creation.

This is a WIP and very much incomplete.

A few of the issues we have with this:

• it's not recommended to alias on the server-side
• we're sending too many events close to the alias, leading to a race condition
• it's not clear whether we should be aliasing to the segment ID or the mixpanel ID

[begedin]

Re:

• we're sending too many events close to the alias, leading to a race condition

We already agreed we should weer of off implicit tracking through Plugs.Segment and instead track explicitly from the controller action.

We did this in other places, but it looks like here, we still implicitly track user created using the plug. This may cause some parallelism, which may be what's causing race conditions.

If we moved tracking to be explicit, we may eliminate this, but I'm not sure.

We would do this by

• removing

def includes?(:create, %CodeCorps.User{}), do: true

from lib/code_corps/analytics/segment_tracking_support.ex

• adding

user_id |> SegmentTracker.track("Signed Up", user)

to the create action

I also think we should add a function clause to CodeCorps.Analytics.SegmentTracker which accepts the user struct as the first argument, instead of just the id, but that's a whole other issue.