MB-8726: updated localhost marker to $HOST

Based on people's feedback

Change-Id: I2c3165936678607cbd1cc548ca287a01ccdfbccf
Reviewed-on: http://review.couchbase.org/30067
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Matt Ingenthron <matt@couchbase.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>