Comment clarification.
Changed embedded code syntax highlighting from python mode to python console mode.
Comments, look and feel.
Added __init__.py to tests/ so tests can be run via setup.py with 'python setup.py test'.
Note the impending deprecation of f.pathstr, f.querystr, and f.fragmentstr from the next version of furl (v0.3.5). Remove documentation references to f.pathstr, f.querystr, and f.fragmentstr.
Changed the default value of scheme, username, password, host, and netloc to None. URLs are now formatted as expected when scheme, username, password, host, and/or netloc are set to '' - that component is included in the URL as an empty string.