Imports of package compactor

PathSynopsis
github.com/coreos/etcd/etcdserver/etcdserverpbPackage etcdserverpb is a generated protocol buffer package.
github.com/coreos/etcd/mvcc
github.com/coreos/pkg/capnslog
github.com/jonboulle/clockwork
golang.org/x/net/contextPackage context defines the Context type, which carries deadlines, cancellation signals, and other request-scoped values across API boundaries and between processes.
syncPackage sync provides basic synchronization primitives such as mutual exclusion locks.
timePackage time provides functionality for measuring and displaying time.