Verify that ActionController::Parameters is not handled as Hash subclass

[karlerikounapuu]

From Rails 5.1, ActionController::Parameters isn't subclass of Hash anymore. To prevent further similar issues such as #1516 , rest of codebase should be checked also for similar pitfalls.

[yulgolem]

Cannot find any occurrences of direct using of old-fashioned params in the model code. That's doesn't mean there is no any, so I suppose we shouldn't close this one yet, just use this issue for future PRs if any.
Let's return to this, say, after a month or so.