MB-8010: update couchbase logo

Change-Id: I48df0ab2a53b859b67ea2126bdd4d846e749cbee
Reviewed-on: http://review.couchbase.org/26369
Reviewed-by: Bin Cui <bin.cui@gmail.com>
Tested-by: Bin Cui <bin.cui@gmail.com>
Merge remote-tracking branch 'origin/2.0.2'

* origin/2.0.2:
  MB-8010: update couchbase logo

Change-Id: I29cec88c29c7cd66c72c12324879e632dda9e9bb