MB-9824 for RAM gauges calculate total and used quota for all nodes

... including those that are down to make them consistent with
bucket details and prevent negative values of "Other Buckets" fields

Change-Id: I8d53f4d1ff0f7062c0b46b368d27521dcb978047
Reviewed-on: http://review.couchbase.org/32530
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>