Add BingPreview crawler (#7160)
Add BingPreview crawler (#7160)

The BingPreview UA appears to be specific to Bing's search app, as documented here: https://blogs.bing.com/webmaster/2012/10/26/page-snapshots-in-bing-windows-8-app-to-bring-new-crawl-traffic-to-sites.
ifduyue/sentry,mvaled/sentry,beeftornado/sentry,mvaled/sentry,beeftornado/sentry,beeftornado/sentry,ifduyue/sentry,mvaled/sentry,looker/sentry,ifduyue/sentry,mvaled/sentry,looker/sentry,looker/sentry,looker/sentry,mvaled/sentry,looker/sentry,ifduyue/sentry,mvaled/sentry,ifduyue/sentry