Added support for nil date input.

lib/i18n_alchemy/date_parser.rb

@@ -40,6 +40,7 @@ def valid_for_localization?(value)
       end
 
       def valid_for_parsing?(value)
+	return false if value.nil?
         !valid_for_localization?(value)
       end
     end

lib/i18n_alchemy/proxy.rb

@@ -61,7 +61,6 @@ def try(*a, &b)
         def method_missing(*args, **kwargs, &block)
           @target.send(*args, **kwargs, &block)
         end
-        ruby2_keywords :method_missing
       else
         def method_missing(*args, &block)
           @target.send(*args, &block)

test/i18n_alchemy/date_parser_test.rb

@@ -6,6 +6,10 @@ def setup
     @date   = Date.new(2011, 12, 31)
   end
 
+  def test_does_not_convert_nil
+    assert_nil @parser.parse(nil)
+  end
+
   def test_does_not_convert_non_string_objects
     assert_equal @date, @parser.parse(@date)
   end