Add space between doxygen class icon and class

The icon spacing on https://commotionwireless.net/developer/api/commotiond/html/annotated.html makes the class list hard to read. This css tweak adds a bit of space between the icon and class name.

To test:
1. Load the doxygen-icons branch in jekyll.
2. Go to /developer/api/commotiond/html/annotated.html
3. The class names should read "C  __class_name", not "C__class_name".