Make Language#find_by_name case insensitive

lib/linguist/language.rb

@@ -7,13 +7,13 @@ module Linguist
     def self.create(name)
       language = new(name)
 
-      @name_index[language.name] = language
+      @name_index[language.name.downcase] = language
 
       language
     end
 
     def self.find_by_name(name)
-      @name_index[name]
+      @name_index[name.downcase]
     end
 
     def self.[](name)

test/test_language.rb

@@ -5,6 +5,12 @@ require 'test/unit'
 class TestLanguage < Test::Unit::TestCase
   include Linguist
 
+  def test_find_by_name
+    assert_equal "Ruby", Language.find_by_name('Ruby').name
+    assert_equal "Ruby", Language.find_by_name('ruby').name
+    assert_equal "Ruby", Language.find_by_name('RUBY').name
+  end
+
   def test_name
     assert_equal "Perl",   Language['Perl'].name
     assert_equal "Python", Language['Python'].name