[bug 867129] Move lazy image rendering from sumo.parser to wiki.parser.

This makes the parser in `apps/sumo/parser.py` render out normal and sane `<img/>`s with the proper `src` attribute. The KB specific parser in `apps/wiki/parser.py` only does the lazy imaging dance now.

I tried to make the template a little less difficult to read by removing the confusing `['lazy', '']` loop.

Also found some fixture declarations that weren't needed and removed them in a separate commit.

r?