Add Credo checks and refactor code

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

Make Logger.debug calls lazy

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

Add missing @moduledocs

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

Refactor according to credo

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

Final fixes and add credo to CI

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

Closes #52

lib/mobilizon/actors/actors.ex

@@ -68,7 +68,7 @@ defmodule Mobilizon.Actors do
              where: u.id == ^user.id
            )
          ) do
-      nil -> get_actors_for_user(user) |> hd
+      nil -> user |> get_actors_for_user() |> hd
       actor -> actor
     end
   end