Delta Recovery: change the color for warning to red

Change-Id: Ib5815e8d7195be6d8ebd797ccaaadd7a73d2bff9
Reviewed-on: http://review.couchbase.org/36662
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>