This starts to fix the scripts so that they load from /usr/lib/crosutils

cros_download_latest_image

Index: cros_download_latest_image
diff --git a/cros_download_latest_image b/cros_download_latest_image
index b3abaf80041d9e15bb60b90b1c3ccd057be104bc..1ef56caad28a187b1ccee7caa6495517fb727425 100755
--- a/cros_download_latest_image
+++ b/cros_download_latest_image
@@ -7,9 +7,26 @@
 # Downloads the latest buildbot image and prints the path to it.
 # This script only works if you have access to buildbot images.
 
-# Load common constants.  This should be the first executable line.
-# The path to common.sh should be relative to your script's location.
-. "$(dirname "$0")/common.sh"
+# --- BEGIN COMMON.SH BOILERPLATE ---
+# Load common CrOS utilities.  Inside the chroot this file is installed in
+# /usr/lib/crosutils.  Outside the chroot we find it relative to the script's
+# location.
+find_common_sh() {
+  local common_paths=(/usr/lib/crosutils $(dirname "$(readlink -f "$0")"))
+  local path
+
+  SCRIPT_ROOT=
+  for path in "${common_paths[@]}"; do
+    if [ -r "${path}/common.sh" ]; then
+      SCRIPT_ROOT=${path}
+      break
+    fi
+  done
+}
+
+find_common_sh
+. "${SCRIPT_ROOT}/common.sh" || (echo "Unable to load common.sh" && exit 1)
+# --- END COMMON.SH BOILERPLATE ---
 
 get_default_board