Improve addition of new peers in Management service. (#56)

* Store refactoring
* Improve addition of new peers in Management service.

management/server.go

@@ -2,13 +2,14 @@ package management
 
 import (
 	"context"
+
 	"github.com/wiretrustee/wiretrustee/management/proto"
 	"google.golang.org/grpc/status"
 )
 
 // Server an instance of a Management server
 type Server struct {
-	Store *Store
+	Store *FileStore
 }
 
 // NewServer creates a new Management server