* Add labels selector (same as List)
* Add fields selector
* Plan to let you select pods by Host and/or Status
* Add resourceVersion to let you resume a watch where you left off.
To make sure the etcd watcher works, I changed the replication
controller to use watch.Interface. I made apiserver support watches on
controllers, so replicationController can be run only off of the
apiserver. I made sure all the etcd watch testing that used to be in
replicationController is now tested on the new etcd watcher in
pkg/tools/.
