Limit the number of results pages which can be returned, to try to deter bots

[m-i-l]

Bots regularly try to get crazy amounts of results simply by appending the page parameter, without actually checking if there are that many pages of results, wasting a lot of CPU resources in the process. For example, a bot has spent hours searching through 10s of 1000s of pages of results for the query "argos garden furniture habitat", via e.g. GET /search/?q=argos+garden+furniture+habitat&page=28802, despite there not being one single result for that query.

Really should return a 404 if the page parameter is above a certain value, e.g. 100, or at the very least not waste CPU time actually performing the search.