Require greenlet 0.3.2 (or later)

Version 0.3.2 resolves a bug that allowed generic "except Exception:"
clauses to catch GreenletExit exceptions.

bug 1097203

Change-Id: Iecf36df36e5eefa45c70fae69c966bcd1f723c8f
Signed-off-by: Zane Bitter <zbitter@redhat.com>
Merge "Require greenlet 0.3.2 (or later)"