Change source directory structure.

Signed-off-by: Kouhei Maeda <mkouhei@palmtb.net>
Rewrite pep8 test code and fixed pep8 violations.

Signed-off-by: Kouhei Maeda <mkouhei@palmtb.net>
Remove unuse modules importing.

Signed-off-by: Kouhei Maeda <mkouhei@palmtb.net>