[zookeeper] host_ports conf parsing breaking

In the zookeeper/views.py line 49
def _get_overview(host_ports):
stats = {}

for s in host_ports.split(','): # But the the host_ports's type is 'str' and value is in the format: "['host_1:port1', 'host_2:port_2', ...]"

1. So we get the string list: "['host_1:port1'", "'host_2:port_2'" ... And then error occurs...
2. I just fix: for s in eval(host_ports): ,And it works!
   host, port = map(str.strip, s.split(':'))

zks = ZooKeeperStats(host, port)
stats[s] = zks.get_stats() or {}

return stats