Since postinst is part of installer, the software updater should depend on the installer package.
Since postinst is part of installer, the software updater
should depend on the installer package.

Move postinst out of customize_rootfs and into the installer
package (at least for now).

Review URL: http://chromereview.prom.corp.google.com/1187059


git-svn-id: 59a3318ba88c04536d83f47c63c52b7f675c4a1a@252 06c00378-0e64-4dae-be16-12b19f9950a1

BugRoger/scripts,zhang0137/scripts,mischief/scripts,smilart/scripts,trnubo/scripts,andrejro/coreos--scripts,BugRoger/scripts,mischief/scripts,glevand/coreos--scripts,nicescale/scripts,trnubo/scripts,vmware/coreos-scripts,andrejro/coreos--scripts,marineam/coreos-scripts,marineam/coreos-scripts,vmware/coreos-scripts,BugRoger/scripts,bcwaldon/coreos-scripts,mjg59/scripts,gtank/scripts,crawford/scripts,endocode/scripts,mjg59/scripts,crawford/scripts,zhang0137/scripts,fivethreeo/scripts,endocode/scripts,sigma/coreos-scripts,nicescale/scripts,crawford/scripts,smilart/scripts,sigma/coreos-scripts,mischief/scripts,bcwaldon/coreos-scripts,coreos/scripts,coreos/scripts,endocode/scripts,vmware/coreos-scripts,sigma/coreos-scripts,trnubo/scripts,mjg59/scripts,bcwaldon/coreos-scripts,gtank/scripts,glevand/coreos--scripts,andrejro/coreos--scripts,gtank/scripts,zhang0137/scripts,smilart/scripts,fivethreeo/scripts,fivethreeo/scripts,nicescale/scripts,marineam/coreos-scripts