fix test run for Emacs 24.5 on travis

Author: tonini

test/elixir-mode-font-test.el

@@ -8,6 +8,8 @@
 
 ;;; Code:
 
+(require 'test-helper)
+
 (defun elixir-test-face-at (pos &optional content)
   "Get the face at POS in CONTENT.
 

test/elixir-mode-indentation-test.el

@@ -9,6 +9,8 @@
 
 ;;; Code:
 
+(require 'test-helper)
+
 (elixir-def-indentation-test indent-use-dot-module-newline
                              (:tags '(indentation))
   "defmodule Foo do