Address comments in code review

Author: Jürgen Hasch

docs/source/exporting.rst

@@ -48,7 +48,7 @@ Converting linked SVG to PDF
 Embedding images in notebooks
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-.. autoclass:: EmbedPreprocessor
+.. autoclass:: EmbedImagesPreprocessor
 
 
 Postprocessors

src/jupyter_contrib_nbextensions/nbconvert_support/pre_embedimages.py

@@ -115,9 +115,9 @@ def replfunc_md(self, match):
             if self.embed_remote_images:
                 data = urlopen(url).read()
             else:
-                return match.string
+                return match.group(0)
         elif url.startswith('attachment'):
-            return match.string
+            return match.group(0)
         else:
             filename = os.path.join(self.path, url)
             with open(filename, 'rb') as f: