MB-8009: update small logo

Change-Id: I64d0e326a7ddb93c1ae974199c1d8f283f938b5b
[alk@tut.by: rebased into branch 2.0.2]
Signed-off-by: Aliaksey Kandratsenka <alk@tut.by>
Reviewed-on: http://review.couchbase.org/26440
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>