MB-26110: Display the data disk read and write failure stats on ...
MB-26110: Display the data disk read and write failure stats on ...

the statistics page in the UI.

Change-Id: I3f1fdb320d114c055f47a9cfe164085ac881504d
Reviewed-on: http://review.couchbase.org/86984
Well-Formed: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Tested-by: Poonam Dhavale <6855f09986fe28ed7e8cdd9d60db878d898703d5@couchbase.com>
Reviewed-by: Artem Stemkovski <15a0730a27c69f62ab86f2b6c639fca202166c02@couchbase.com>

membase/ns_server,membase/ns_server,membase/ns_server,membase/ns_server,membase/ns_server,membase/ns_server