[Enhancement] Custom media lifecycle scripts (#219)

* Namespaced notification modules under lifecycle

* Added a JSON encoder for all the main model types

* Added startup task to create user script file

* Hook up user script event to media download

* Hooked up media deletion user script

* Added jq to docker deps

* Updated README

test/pinchflat_web/controllers/media_item_controller_test.exs

@@ -1,11 +1,14 @@
 defmodule PinchflatWeb.MediaItemControllerTest do
   use PinchflatWeb.ConnCase
 
+  import Mox
   import Pinchflat.MediaFixtures
 
   alias Pinchflat.Repo
   alias Pinchflat.Downloading.MediaDownloadWorker
 
+  setup :verify_on_exit!
+
   describe "show media" do
     setup [:create_media_item]
 
@@ -49,6 +52,7 @@ defmodule PinchflatWeb.MediaItemControllerTest do
   describe "delete media" do
     setup do
       media_item = media_item_with_attachments()
+      stub(UserScriptRunnerMock, :run, fn _event_type, _data -> :ok end)
 
       %{media_item: media_item}
     end