Follow PEP 8 - Style Guide for Python Code

PEP 8 is a style guide which a widely areed and used in the Python
community. Follow it could encourage more Python developers to join
the development.

This commit changes the code to follow all rules expect PEP 8, except
E501 - the 80 chars limitation of the each lines. For modern programs,
120 chars is comfortable.

There are 181 volations of PEP 8 in the project:

$ flake8 setup.py weibo.py snspy.py | grep -v E501 | wc -l
181

All of the volations have been fixed:

$ flake8 setup.py weibo.py snspy.py | grep -v E501 | wc -l
0

Signed-off-by: Tom Li <biergaizi@members.fsf.org>