client/signal: Revert "add signal 'snapshot', rename existing signal 'wakeup' to 'replication'"

This was merged to master prematurely as the job components are not decoupled well enough
for these signals to be useful yet.

This reverts commit 2c8c2cfa14.

closes #452

daemon/control.go

@@ -143,12 +143,10 @@ func (j *controlJob) Run(ctx context.Context) {
 
 			var err error
 			switch req.Op {
-			case "replication":
-				err = j.jobs.doreplication(req.Name)
+			case "wakeup":
+				err = j.jobs.wakeup(req.Name)
 			case "reset":
 				err = j.jobs.reset(req.Name)
-			case "snapshot":
-				err = j.jobs.dosnapshot(req.Name)
 			default:
 				err = fmt.Errorf("operation %q is invalid", req.Op)
 			}