Renamed rss.pt to rss.pt.xml because zptlint should ignore this file.
Otherwise we get "zope.tal.taldefs.TALError: empty HTML tags cannot use tal:content: 'link'"
"<link></link>" not valid for a pt file (in rss 2 it is).
Fix C901 method is too complex for vocaularies.py
Fix C901 "method" is too complex for migration.py
Fix C901 "method" is too complex for setuphandler.py
Merge pull request #77 from plone/fix-flake8

Fixed Flake8/McCabe violations