Revert "new guardian version"

This reverts commit bc34359127526d1e04990ba9f5d86e7f6c91f7b3.

The guardian app is removed from the project in branch rm_guardian which branches off from the production system state;
it will be applied to the production system in two steps: first checkout tag rm_guardian_1, then migrate to empty
guardian tables from the DB; then checkout tag rm_guardian_2 to remove guardian folder and app. This would conflict
with the guardian app update which I, meanwhile, had performed on the main development strand. That's why I am
now reverting the update (affects two commits).
Revert "delete previous guardian version"

This reverts commit bfc99d6c2bba62d1afa5391676b003ba5fa88b31.

Step two of reverting the guardian update. Guardian will be removed from project. See previous commit for details.