We need to be able to generate URL slugs for media entries.

I'd really like to use
`http://flask.pocoo.org/snippets/5/ <http://flask.pocoo.org/snippets/5/>`_
but have to clear it with the FSF that that public domain assertion
is okay for our codebase and to merge.

Regardless, we need to generate slugs for each entry anyway.
Probably during the submission phase after setting the title there
should be an entry.generate\_slug() method which sets the slug on
the MediaEntry instance.

This way we have a nice way of accessing for example the fictional
address:

[http://mediagoblin.example.org/\ :sub:`cwebber/w/a-walk-in-the-park/](http://mediagoblin.example.org/`\ cwebber/w/a-walk-in-the-park/)

that last bit of the URL being the entry slug.

The user bio should be Markdown enabled with the
``mediagoblin.util.cleaned_markdown_conversion()`` function.

Proposal:


-  Add a field to User (``mediagoblin/db/models.py``) which is
   named ``bio_html`` (see the description\_html field in
   ``MediaEntry`` [same file] for refernce).
-  When the user updates the bio field
   (``mediagoblin/edit/views.py:edit_profile()``), run the
   ``cleaned_markdown_conversion()`` and put the output in the
   ``bio_html`` field.
-  Edit ``mediagoblin/templates/mediagoblin/utils/profile.html`` to
   output ``user.bio_html`` instead of ``user.bio`` and to NOT
   autoescape the output of ``{{ user.bio_html }}`` (see
   @mediagoblin/templates/mediagoblin/user\_pages/media.html for
   reference).

Right now, comments only appear after the new comment form on the
photo page. This makes them really easy to miss, so far down the
page.

Let's put the comments ahead of the new comment form -- so you
(hopefully) read what other people have written before writing
something new!