Allow disabling certain scrapers in a request

[TheTechRobo]

Some users might have already checked e.g. the Wayback Machine. Because of how slow it is, they might not want to do it again.

[TheTechRobo]

With #66 implemented, I no longer see this as helpful. In fact, people might think they've checked a source, but some places require specific methods to know for certain whether it's archived (e.g. the Wayback Machine).