Fix numerous style nits and inconsistencies in mod_image_for_test.sh
Fix numerous style nits and inconsistencies in mod_image_for_test.sh

BUG=none
TEST=build and boot a factory test image

Review URL: http://codereview.chromium.org/6713049

Change-Id: Ia0c4c9780fccc91c4464acf84ca4c0327b8ea7bd

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