Bump version 0.4.0

Author: edgurgel

mix.exs

@@ -8,7 +8,7 @@ defmodule Solid.Mixfile do
   def project do
     [
       app: :solid,
-      version: "0.3.0",
+      version: "0.4.0",
       elixir: "~> 1.9",
       build_embedded: Mix.env() == :prod,
       start_permanent: Mix.env() == :prod,