Added first portion of logging adaptation.

Things may be broken at this point - there are still several modules to
be adapted.

ebook_converter/ebooks/txt/markdownml.py

@@ -43,7 +43,8 @@ class MarkdownMLizer(OEB2HTML):
     def mlize_spine(self, oeb_book):
         output = ['']
         for item in oeb_book.spine:
-            self.log.debug('Converting %s to Markdown formatted TXT...' % item.href)
+            self.log.debug('Converting %s to Markdown formatted TXT...',
+                           item.href)
             self.rewrite_ids(item.data, item)
             rewrite_links(item.data, partial(self.rewrite_link, page=item))
             stylizer = Stylizer(item.data, item.href, oeb_book, self.opts, self.opts.output_profile)