etcd_tools.go is not dependent on the specific implementation
(which is provided by pkg/api). All EtcdHelpers are created
with an encoding object which handles Encode/Decode/DecodeInto.
Additional tests added to verify simple atomic flows.
Begins to break up api singleton pattern.
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/.
