tag clouds

[Caleb Davis]

This is another rollover from `#360 </issues/360>`_, but it got
left behind somehow. A tag cloud is a dict-like object containing
{'tag-name':frequency-of-use,...}. It's fun to have them to see all
the tags that people are using publicly on an instance.

Where would we display these?


-  instance home page - all users, processed media
-  user's profile - user's processed media
-  [BONUS] - arbitrary collection (/tags/bunnies) Open questions:
-  Should we use MapReduce?
   `http://cookbook.mongodb.org/patterns/count\_tags/ <http://cookbook.mongodb.org/patterns/count_tags/>`_
   The alternative would be to write tags to a text file and do

   sort tags\_text\_file \| uniq -c


or do it completely within python \* Should we use celery?
Generating tag clouds shouldn't slow page renders. Thoughts:

    do it with python if you're using MapReduce since, if MapReduce
    gets too slow, you just add more processors!


    if it 'takes too long', then use celery



-  How often do we update the clouds? Thoughts included:

    not during a bulk upload



-  How do we store these tag cloud objects? If we're not rendering
   them on the fly, then they should be in some kind of cache.
   Thoughts:

    user['tag\_cloud'] = dict


    associate the cloud with the route. something like -
    {'/':'instance\_cloud.txt','/u/user1':'user1\_cloud.txt','/tags/bunnies':'tags\_bunnies.txt'}