[cbcollect_info] added flag to get per-process diag from one node

So that we can run cbcollectinfo on all nodes concurrently.

Change-Id: Icf9a3fa70fc86071bb1799e23ff8c7ddf9af3e35
Reviewed-on: http://review.couchbase.org/37284
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Artem Stemkovski <artem@couchbase.com>