pep8: cleaned up excludes

pep8: cleaned up excludes

Don't over-exclude files from pep8 automation. Specifically, tools/*
should maintain common Python style as any other Neutron code.

Don't exclude every single dot-file/dot-dir separately but instead
apply .* wildcard.

Drop rally-scenarios exclusion. First, the directory is now rally-jobs,
so exclusion didn't work. Second, it's better to also apply pep8 checks
for those files (there are some Python files inside the directory).

Change-Id: Ife1d8a538c1bdddac30ca1c30c48a71564860624