Testing '#:' attribute docstrings for sphinx.

This is supposed to work and give us class/instance docstrings, but it's not
yet.  I have a question on the sphinx list about it, let's leave it in the
code until we figure out what we need to do to sphinx for it to work (it
doesn't hurt otherwise).

IPython/core/application.py

@@ -90,7 +90,7 b' class Application(object):'
     default_log_level = logging.WARN
     # Set by --profile option
     profile_name = None
-    # User's ipython directory, typically ~/.ipython/
+    #: User's ipython directory, typically ~/.ipython/
     ipython_dir = None
 
     # Private attributes