Add junit formatter for tests

mix.exs

@@ -141,6 +141,7 @@ defmodule Pleroma.Mixfile do
       {:benchee, "~> 1.0"},
       {:esshd, "~> 0.1.0", runtime: Application.get_env(:esshd, :enabled, false)},
       {:ex_rated, "~> 1.3"},
+      {:junit_formatter, "~> 3.0", only: [:test]},
       {:plug_static_index_html, "~> 1.0.0"},
       {:excoveralls, "~> 0.11.1", only: :test}
     ] ++ oauth_deps()