MB-8157: update couchbase favicon.ico

Change-Id: Ife431f2924e340bdc3363c3780f450d01651bc47
Reviewed-on: http://review.couchbase.org/25924
Reviewed-by: Pavel Blagodov <stochmail@gmail.com>
Tested-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>