Make markdown, pygments, and docutils dependencies optional.
Fix requirements for pip/PyPI
Doh! I forgot that yaml has built in iso8601 time stamp support.
We don't need fancy libraries and funny code to use it. Just make sure
it exists under the right name.
Apparently page's did not have a guranteed datetime field yet. Oops!
Refactor wok.py to be a class.
Depend on yaml as well.
Now it is a installable python package! (I think...)