This commit fixes pep8 issues that were added when subunit2html was
copied into the repo. As part of this the subunit2html was missing a
license header for the additions made to it on top of the original
HTMLTestRunner script it was based on. The addition of the copyright
header mirrors project-config change:
I6fc16d316012fd3e1c196f74df25d725a310f6dc
Change-Id: Ieb42d5baddb3e1446fcd50197136f605324323aa
12ca9dd582