Make study listings async

This is a first attempt start at making things async. As an example, this makes the creation of the study listings async so the loading is non-blocking or other pages.
This is going to be extremely slow, no? As every time that we need to display a list of studies we need to loop between all of them. Will it be better to do this directly in the DB? Have something like `Study.public()`, `User.shared_studies()`, `User.private_studies()`