Add sudo_clobber and sudo_append functions so that we can "echo"  and "cat" stuff and pipe it to something that can write to a file as root. For example:
Add sudo_clobber and sudo_append functions so that we can "echo"
 and "cat" stuff and pipe it to something that can write to a
file as root. For example:

echo "foo" | sudo_append /tmp/bar

will append "foo" to the file /tmp/bar as root. While

echo "foo" | sudo_clobber /tmp/bar

will truncate /tmp/bar and then write "foo" to the file.

Review URL: http://codereview.chromium.org/1610021

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