Version bump 0.0.5-dev
Avoid importing argparse if python > 2.7

A warning is displayed if argparse is imported twice.
Add requirements-extra-python2.6.txt and move argparse into it
Get ride of html5lib dependency.

The parser provided by BeautifulSoup 4.2.0 is able to successfully parse the pages.
Add a Known issues section.

Warn that version < 0.0.4 no longer work.
Warn that BeautifulSoup 4.2.0 is broken with 0.0.4