Add test timers via nose-timer plugin; list the 10 slowest by default

tox.ini

@@ -4,10 +4,11 @@ envlist = py26, py27, pypy
 deps =
     unittest2
     nose
+    nose-timer
     coverage
     mock
     python-snappy
 commands =
-    nosetests {posargs:-v --with-id --with-coverage --cover-erase --cover-package kafka}
+    nosetests {posargs:-v --with-id --with-timer --timer-top-n 10 --with-coverage --cover-erase --cover-package kafka}
 setenv =
     PROJECT_ROOT = {toxinidir}