Add _random_docs?limit=5

I think it would be useful to be able to retrieve multiple random docs, limited by a certain amount of documents. By default it should probably be just 5 or something, because it could get somewhat inefficient with a high number of docs. Returned docs should be unique. Order could be random too.

Now that I think about it, wouldn't it make sense to be able to get random entries from a view (instead)?