doc: fix bitbucket links after relocation to separate account
wsgi: minimum_chunk_size of last Server altered all previous (global variable)
tests: Improve tox configuration and setup Travis
Travis: Allow independent tests to run in parallel

Add py25 to allowed failures
tests: select socket pair is not writable; Thanks to Yamamoto Takashi
green: select: ensure that hub can .wait() at least once before timeout

https://github.com/eventlet/eventlet/pull/25
support: do not clear sys.exc_info if can be preserved (greenlet >= 0.3.2)