add build directive to instance.go too
add build directive to instance.go too

Signed-off-by: Tycho Andersen <10c18fcb898ee6b17d6575d444b125d10b3f4d6a@canonical.com>

macgreagoir/juju,marcmolla/juju,AdamIsrael/juju,mjs/juju,alesstimec/juju,waigani/juju,bac/juju,gabriel-samfira/juju,frankban/juju,bz2/juju,mjs/juju,gabriel-samfira/juju,perrito666/juju,mikemccracken/juju,dooferlad/juju,davecheney/juju,mjs/juju,axw/juju,marcmolla/juju,perrito666/juju,howbazaar/juju,bogdanteleaga/juju,reedobrien/juju,dimitern/juju,gabriel-samfira/juju,bac/juju,dooferlad/juju,alesstimec/juju,frankban/juju,bz2/juju,macgreagoir/juju,anastasiamac/juju,alesstimec/juju,reedobrien/juju,dimitern/juju,howbazaar/juju,howbazaar/juju,macgreagoir/juju,perrito666/juju,frankban/juju,dooferlad/juju,ericsnowcurrently/juju,axw/juju,mikemccracken/juju,AdamIsrael/juju,mikemccracken/juju,AdamIsrael/juju,makyo/juju,ericsnowcurrently/juju,davecheney/juju,anastasiamac/juju,mjs/juju,kat-co/juju,kat-co/juju,waigani/juju,perrito666/juju,dimitern/juju,bac/juju,bogdanteleaga/juju,mikemccracken/juju,howbazaar/juju,kat-co/juju,howbazaar/juju,dooferlad/juju,axw/juju,alesstimec/juju,anastasiamac/juju,bz2/juju,bac/juju,ericsnowcurrently/juju,dooferlad/juju,alesstimec/juju,mjs/juju,AdamIsrael/juju,waigani/juju,axw/juju,makyo/juju,frankban/juju,ericsnowcurrently/juju,dimitern/juju,marcmolla/juju,ericsnowcurrently/juju,gabriel-samfira/juju,anastasiamac/juju,bac/juju,axw/juju,reedobrien/juju,bz2/juju,macgreagoir/juju,marcmolla/juju,mikemccracken/juju,mjs/juju,perrito666/juju,waigani/juju,makyo/juju,davecheney/juju,mjs/juju,kat-co/juju,anastasiamac/juju,davecheney/juju,bogdanteleaga/juju,kat-co/juju,makyo/juju,frankban/juju,bogdanteleaga/juju,marcmolla/juju,bz2/juju,gabriel-samfira/juju,dimitern/juju,reedobrien/juju,macgreagoir/juju,reedobrien/juju