Feature: Persistence

Handle updating of models and database via API calls.

TODO:
add endpoints to add audio flies and images.
Unused block argument - `a`. If it's necessary, use `_` or `_a` as an argument name to indicate that it won't be used. Also consider using a proc without arguments instead of a lambda if you want it to accept any arguments but don't care about them.<br>Redundant `self` detected.<br>Space missing to the left of {.