Renamed page.meta_data to page.metadata for consistency with views

test/test_page.rb

@@ -231,7 +231,7 @@ context "within a sub-directory" do
   test "get metadata on page" do
     page = @wiki.page('Elrond')
     assert_equal Gollum::Page, page.class
-    assert_equal 'elf', page.meta_data['race']
+    assert_equal 'elf', page.metadata['race']
   end
 
 end