Let nose run s3tests in parallel.

This decreases the run time significantly.

Unfortunately, there seem to be cleanup-related bugs
in parallel runs for now. It's not safe to actually
run with --processes=N >1 yet, but at least the right
magic incantation is now recorded.

s3tests/functional/__init__.py

@@ -71,6 +71,9 @@ def nuke_prefixed_buckets(prefix):
     print 'Done with cleanup of test buckets.'
 
 
+# nosetests --processes=N with N>1 is safe
+_multiprocess_can_split_ = True
+
 def setup():
 
     cfg = ConfigParser.RawConfigParser()