Fix some invalid error messages from Mix

Author: José Valim

lib/mix/lib/mix/tasks/escriptize.ex

@@ -130,7 +130,7 @@ defmodule Mix.Tasks.Escriptize do
 
   defp app_tuples(app) do
     case :code.where_is_file('#{app}.app') do
-      :non_existing -> raise Mix.Error, "Could not find application #{app}"
+      :non_existing -> raise Mix.Error, message: "Could not find application #{app}"
       file -> get_tuples(Path.dirname(Path.dirname(file)))
     end
   end

lib/mix/lib/mix/tasks/test.ex

@@ -82,8 +82,8 @@ defmodule Mix.Tasks.Test do
     { opts, files } = OptionParser.parse(args, switches: @switches)
 
     unless System.get_env("MIX_ENV") || Mix.env == :test do
-      raise Mix.Error, "mix test is running on environment #{Mix.env}. If you are " <>
-                       "running tests along another task, please set MIX_ENV explicitly"
+      raise Mix.Error, message: "mix test is running on environment #{Mix.env}. If you are " <>
+                                "running tests along another task, please set MIX_ENV explicitly"
     end
 
     Mix.Task.run "app.start", args