re-enable some tweaks commented out by 049545ae
re-enable some tweaks commented out by 049545ae

To enable config/software that pulls from private git repositories we 
need the following tweaks to the local build system:

* StrictHostKeyChecking disabled for github.com
* SSH_AUTH_SOCK honored under sudo
mattray/omnibus,szechyjs/omnibus,higanworks/omnibus,rhass/omnibus,servebox/omnibus,Scalr/omnibus,Altiscale/omnibus,intfrr/omnibus,3ofcoins/chef-omnibus,sh9189/omnibus,strangelittlemonkey/omnibus,jamesn/omnibus,mattray/omnibus,mattray/omnibus,DataDog/omnibus-ruby,rapid7/omnibus,hugosato/omnibus,servebox/omnibus,Altiscale/omnibus,intfrr/omnibus,Altiscale/omnibus,rapid7/omnibus,pskrz/omnibus,Scalr/omnibus,servebox/omnibus,rapid7/omnibus,adamleff/omnibus,sh9189/omnibus,DataDog/omnibus-ruby,sh9189/omnibus,rhass/omnibus,chef/omnibus,lvfeng1130/omnibus,strangelittlemonkey/omnibus,ashhher3/omnibus,rhass/omnibus,DataDog/omnibus-ruby,lvfeng1130/omnibus,jamesn/omnibus,Scalr/omnibus,szechyjs/omnibus,ashhher3/omnibus,chef/omnibus,strangelittlemonkey/omnibus,3ofcoins/chef-omnibus,szechyjs/omnibus,3ofcoins/chef-omnibus,intfrr/omnibus,ashhher3/omnibus,higanworks/omnibus,chef/omnibus,higanworks/omnibus,lvfeng1130/omnibus,hugosato/omnibus,jamesn/omnibus,adamleff/omnibus,hugosato/omnibus,adamleff/omnibus,pskrz/omnibus,pskrz/omnibus