sign_official_build.sh: rename "install" to "factory"

This lines up with the terminology that people have been using, and the
valid types that can appear in signer instruction files.  We keep around
the old "install" so that other code continues to work.

BUG=None
TEST=None
BRANCH=none

Change-Id: I8d0d2ab4c0ae61f6bcdbcc24ec9796d9eabe386e
Reviewed-on: https://gerrit.chromium.org/gerrit/33056
Reviewed-by: David McMahon <djmm@chromium.org>
Commit-Ready: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>

scripts/image_signing/sign_official_build.sh

@@ -27,7 +27,8 @@ Usage: $PROG <type> input_image /path/to/keys/dir [output_image] [version_file]
 where <type> is one of:
              ssd  (sign an SSD image)
              recovery (sign a USB recovery image)
-             install (sign a factory install image)
+             factory (sign a factory install image)
+             install (old alias to "factory")
              firmware (sign a firmware image)
              usb  (sign an image to boot directly from USB)
              verify (verify an image including rootfs hashes)
@@ -628,7 +629,7 @@ elif [ "${TYPE}" == "recovery" ]; then
     ${KEY_DIR}/recovery_kernel_data_key.vbprivk \
     2
   sign_for_recovery ${OUTPUT_IMAGE}
-elif [ "${TYPE}" == "install" ]; then
+elif [ "${TYPE}" == "factory" ] || [ "${TYPE}" == "install" ]; then
   cp ${INPUT_IMAGE} ${OUTPUT_IMAGE}
   resign_firmware_payload ${OUTPUT_IMAGE}
   update_rootfs_hash ${OUTPUT_IMAGE} \