Add basic configuration management module.

test/config_test.exs

@@ -0,0 +1,10 @@
+defmodule Pleroma.ConfigTest do
+  use Pleroma.DataCase
+  alias Pleroma.Config
+
+  test "get returns the item at the path if there is one" do
+    Config.put([:instance, :name], "Plemora")
+    assert Config.get([:instance, :name]) == "Plemora"
+    assert Config.get([:unknown]) == nil
+  end
+end