feat(registry): deis-cache for saving meta data

This improves the registry speed with remote stores and improves the developer UX

Fixes #1780, fixes #1794
let's check `ECodeKeyNotFound` instead of hardcoding the error code here

https://github.com/coreos/etcd/blob/34dabe281b8394851dd6676fd80274d9ceeeaa6e/error/error.go#L77