Code cleanup (PEP8 and documentation)

I'm currently reading the ckan code, so I decided to do some cleanups along the way.
With these two commits I made ``logic/action`` pep8 compliant, as you can see from::

    pep8  --ignore=E711,E712 ckan/logic/action

(The ignores are for "cond == Null`` and ``cond == True``, used in the SQLAlchemy queries)