Add feature to index and search boorus

[ghost]

Issue for planned feature to allow for indexing and searching various boorus.

[ghost]

If the sites in question have their own search API, we could utilize that perhaps, or else begin crawling them at some point. When someone does make a search, it might be wise to cache the results in case someone does so again to reduce the number of requests. Cache could be updated either on request or after some amount of time since the last cache.

[ghost]

I think a better idea is to make a list of search formats for various domains.