Add Zookeeper to tests

Add a requirement on kazoo and add a Zookeeper chroot to the test
infrastructure.

This is based on similar code in Nodepool.

Change-Id: Ic05386aac284c5542721fa3dcb1cd1c8e52d4a1f
diff --git a/bindep.txt b/bindep.txt
index a2cc02e..b0c4c3b 100644
--- a/bindep.txt
+++ b/bindep.txt
@@ -1 +1,2 @@
 libjpeg-dev [test]
+zookeeperd [platform:dpkg]