- add mix.exs because rebar3 hex isn't working well

with Erlang... You can see how to make this file
   here: https://hex.pm/docs/publish.

mix.exs

@@ -0,0 +1,41 @@
+defmodule Postgrex.MixProject do
+  use Mix.Project
+
+  def project() do
+    [
+      app: :bencode,
+      version: "0.1.0",
+      elixir: "~> 1.0",
+      build_embedded: Mix.env == :prod,
+      start_permanent: Mix.env == :prod,
+      description: description(),
+      package: package(),
+      deps: deps(),
+      name: "Bencode",
+      source_url: "https://github.com/niamtokik/bencode"
+    ]
+  end
+
+  def application() do
+    []
+  end
+
+  defp deps() do
+    []
+  end
+
+  defp description() do
+    "Bencode Erlang Library"
+  end
+
+
+  defp package() do
+    [ name: "bencode",
+      files: ["rebar.config", "mix.exs", "README.md", "LICENSE",
+              "src/*.erl", "src/*.src"],
+      maintainers: ["Mathieu Kerjouan"],
+      licenses: ["BSD-4"],
+      links: %{"GitHub" => "https://github.com/niamtokik/bencode"}
+    ]
+  end
+end