Add support for ostree static-delta delete

Closes: #245
Approved by: giuseppe

src/libostree/ostree-cmdprivate.c

@@ -46,7 +46,8 @@ ostree_cmd__private__ (void)
 {
   static OstreeCmdPrivateVTable table = {
     impl_ostree_generate_grub2_config,
-    _ostree_repo_static_delta_dump
+    _ostree_repo_static_delta_dump,
+    _ostree_repo_static_delta_delete
   };
 
   return &table;