Facebook scraper does not detect login redirects

When one's IP gets banned from Facebook, everything redirects to the login page, but the Facebook module does not detect that and instead claims that everything's fine without results.

(Via @Huertas97 in #249)

Start by locating the Facebook scraper module and tracing how it handles responses that produce no results. Reproduce the banned-IP behavior if possible, then verify that a redirect to Facebook's login page is detected instead of reported as a successful empty result.

Written by the indexing model from the issue text.