Fixup return from MockInfo

The MockInfo command should return a JSON object with the same
format as all of the other commands

Change-Id: Ide3c609e3871fa131a4682abb2742dc82e354838
Reviewed-on: http://review.couchbase.org/27925
Reviewed-by: Mark Nunberg <mnunberg@haskalah.org>
Tested-by: Trond Norbye <trond.norbye@gmail.com>