Curently tox ignores H405, D105, D200, and D203.
H405: multi line docstring summary not separated with an empty line.
D105: Missing docstring in magic method.
D200: One-line docstring should fit on one line with quotes.
D203: 1 blank required before class docstring.
This patch removes tox ignores and fix docstrings.
Change-Id: Ia3ac9796630e24ce04dc9f38a8d944334d6978d2