Mechanical execution of:
```
git mv ./pkg/mock/mockserver ./client/pkg/mock
git mv ./pkg/mock/{mockstorage,mockstore,mockwait} ./server/pkg/mock
```
The packages depend on etcd API / protos - so they are NOT etcd-dependencies.
In such situation thay should be placed in 'pkg' folder.
pkg/ is a collection of utility packages used by etcd without being specific to etcd itself. A package belongs here
only if it could possibly be moved out into its own repository in the future.