Installer: deallocate ports upon app uninstall

Change-Id: I19298537fed02de03a9e74fa351cf23f733de699
diff --git a/core/installer/app.go b/core/installer/app.go
index e443948..0eaa27d 100644
--- a/core/installer/app.go
+++ b/core/installer/app.go
@@ -83,6 +83,7 @@
 type PortForward struct {
 	Allocator     string `json:"allocator"`
 	ReserveAddr   string `json:"reservator"`
+	RemoveAddr    string `json:"deallocator"`
 	Protocol      string `json:"protocol"`
 	SourcePort    int    `json:"sourcePort"`
 	TargetService string `json:"targetService"`