MB-12222: hot servers section fixes

Change-Id: If6ddfa5af03768e0e688ff5ee2e81987a7efe31f
Reviewed-on: http://review.couchbase.org/41905
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
MB-12222: serialize data of every request to the server

Change-Id: Iffb32d3bcfb323276b4108336af9d8e2f0267050
Reviewed-on: http://review.couchbase.org/41906
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>