Add build iteration to `*.metadata.json`
Add build iteration to `*.metadata.json`

This information is important in various package publishing activities.

lvfeng1130/omnibus,szechyjs/omnibus,chef/omnibus,Altiscale/omnibus,sh9189/omnibus,servebox/omnibus,adamleff/omnibus,servebox/omnibus,Altiscale/omnibus,Scalr/omnibus,higanworks/omnibus,rhass/omnibus,adamleff/omnibus,intfrr/omnibus,adamleff/omnibus,intfrr/omnibus,hugosato/omnibus,mattray/omnibus,chef/omnibus,rhass/omnibus,DataDog/omnibus-ruby,ashhher3/omnibus,mattray/omnibus,strangelittlemonkey/omnibus,DataDog/omnibus-ruby,ashhher3/omnibus,higanworks/omnibus,chef/omnibus,jamesn/omnibus,szechyjs/omnibus,pskrz/omnibus,Scalr/omnibus,jamesn/omnibus,strangelittlemonkey/omnibus,rapid7/omnibus,rapid7/omnibus,Altiscale/omnibus,lvfeng1130/omnibus,jamesn/omnibus,pskrz/omnibus,hugosato/omnibus,higanworks/omnibus,3ofcoins/chef-omnibus,3ofcoins/chef-omnibus,mattray/omnibus,szechyjs/omnibus,pskrz/omnibus,Scalr/omnibus,sh9189/omnibus,sh9189/omnibus,rapid7/omnibus,rhass/omnibus,DataDog/omnibus-ruby,servebox/omnibus,lvfeng1130/omnibus,ashhher3/omnibus,hugosato/omnibus,intfrr/omnibus,strangelittlemonkey/omnibus,3ofcoins/chef-omnibus