Gather ssl_proxy logs as part of diag.

Change-Id: I8408d6707c50db11a34fe28d849c7d48bef7dbfd
Reviewed-on: http://review.couchbase.org/35476
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>