Allow user to override chroot command.
some documentation.
pass chroot command to /bin/sh

this allows us to specify an arbitrary chroot command, i.e. for sudo
notes/reorg.
wip
Merge branch 'master' into 430
wip
Revert "notes/reorg."

This reverts commit 73c5aec24d0a504ecfbae038b4b7effb54adb929.

Conflicts:
	builder/amazon/chroot/step_copy_files.go
using blocking cp method.
bugfix.
Unit tests.
We're not using this log package.
Merge remote-tracking branch 'origin/master' into 430
get chroot command from proper place.
bugfixes, wip
wip
fix chroot Upload command.
replace command config with wrapper command.
fixing up types.
building but there's an exec error.