add install to arm platform
add install to arm platform

now we could install to mmcblk0.
for vogue, we even change the uboot environment.
on Samsung, you had to use 'chromeos-install --skip_src_removable' because mmcblk1 is not removable somehow.

Review URL: http://codereview.chromium.org/1618013

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