added test for buffer that are bigger than max int. That causes waitress
function to throw exception when calling __len__ on them since
python requires returing int from __len__ function of object
proposed fix for issue #22
Merge branch 'issue-22-fix' of https://github.com/marcinkuzminski/waitress into marcinkuzminski-issue-22-fix
Change log for PR #25.

Fixes #22.