Update zk library to use our fork.

[claygoddard]

Use our fork for now to fix some session lost issues.
Additionally, update import package to reference new package name.

[claygoddard]

Need to do this first so that the packages match up when I update our internal repo.

[donjaime]

Seems reasonable. But I will defer to Jh and Scottb.

[dragonsinth]

LGTM, but why not just reference fullstorydev/zk in code instead of using a replace directive? Until we can get a patch landed go-zookeeper/zk#34 -- and there doesn't seem to be much interest in it :( -- this lib won't work with any other version of zk.

[claygoddard]

LGTM, but why not just reference fullstorydev/zk in code instead of using a replace directive? Until we can get a patch landed go-zookeeper/zk#34 -- and there doesn't seem to be much interest in it :( -- this lib won't work with any other version of zk.

That's fair. Was doing it for clarity, but I'll just point directly.