Add option to require UUID hash or partial UUID during crawl

[ThiefMaster]

Currently crawling just accesses the data endpoint on the crawled instance and takes the data from there. It does not validate that the instance is still registered with the same UUID. This is a bit annoying when the same instance is registered more than once, as we have no way to know which one is the current registration.

The idea here is to include a new field in the data endpoint (e.g. in Indico) that includes e.g. the last few digits from the instance's UUID or a hash of the whole UUID. Then we can check while crawling if the UUID still matches and discard the data if it doesn't or somehow flag it.