The connect string spec for ZooKeeper is a little funky, I'll agree. From their docs "127.0.0.1:3000,127.0.0.1:3001,127.0.0.1:3002/app/a" is the general form. If we are going to use something other than the raw connect string, we most definitely need to include a chroot in addition to host:port pairs.

E.g., 
```python
def collection_hosts(hosts=[], chroot="", randomize=True):
    ...
```