Allows Typogrify to ignore user specified tags. Refs #1407

Typogrify interferes with certain sections of the output that it should not touch (see #1407 for more details).
This feature adds a setting called TYPOGRIFY_IGNORE_LIST which is a list of tag for Typogrify to ignore.

The following was updated:

 1. readers.py - if TYPOGRIFY_IGNORE_TAGS is present, then use it
 2. settings.ps - default TYPOGRIFY_IGNORE_TAGS to []
 3. contents/article_with_code_block.rst - an article with a code block for typogrify to ignore
 4. updated tests
 5. updated documentation

pelican/tests/test_generators.py

@@ -114,6 +114,8 @@ class TestArticlesGenerator(unittest.TestCase):
              'article'],
             ['This is an article without category !', 'published',
              'TestCategory', 'article'],
+            ['An Article With Code Block To Test Typogrify Ignore',
+              'published', 'Default', 'article'],
             ['マックOS X 10.8でパイソンとVirtualenvをインストールと設定', 'published',
              '指導書', 'article'],
         ]