Prune trailing whitespaces from code and documentation

They are redundant in all pruned cases and sometimes even create some
problems, e.g., when one tries to jump through paragraphs in vi.

Signed-off-by: Eygene Ryabinkin <rea@codelabs.ru>

offlineimap/__init__.py

@@ -14,6 +14,6 @@ __homepage__ = "http://offlineimap.org"
 banner = __bigcopyright__
 
 from offlineimap.error import OfflineImapError
-# put this last, so we don't run into circular dependencies using 
+# put this last, so we don't run into circular dependencies using
 # e.g. offlineimap.__version__.
 from offlineimap.init import OfflineImap