This is so that multiple users can be paired with a single list.
In the future, we may want to reconsider list deletion behavior to simply remove a user's access and only delete it when no one has access.
We may also want the user deletion Lambda to use the list deletion Lambda when it is created.
Build out infrastructure for get requests (along with the first couple).
This includes changing the request engine from Volley to OKHTTP due to issues get Volley's callbacks to call back.
