refactor(anti-spam): make anti-spam agnostic from Akismet

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

lib/service/anti_spam/anti_spam.ex

@@ -0,0 +1,17 @@
+defmodule Mobilizon.Service.AntiSpam do
+  @moduledoc """
+  Module to load the service adapter defined inside the configuration.
+
+  See `Mobilizon.Service.AntiSpam.Provider`.
+  """
+
+  @doc """
+  Returns the appropriate service adapter.
+
+  According to the config behind
+    `config :mobilizon, Mobilizon.Service.AntiSpam,
+       service: Mobilizon.Service.AntiSpam.Module`
+  """
+  @spec service :: module
+  def service, do: get_in(Application.get_env(:mobilizon, __MODULE__), [:service])
+end