Instruct pep8/flake8 to ignore lines too long

There is a lot of overly long lines (more than 79 characters).  I am not
sure it is worth fixing them so just instruct flake8 and pep8 to ignore
them entirely (error E501).
Merge pull request #21 from hashar/pep8-ignores

Instruct pep8/flake8 to ignore lines too long