Add tools library for cros_bundle_firmware
Add tools library for cros_bundle_firmware

This library provides functions to run tools with given verbosity,
reading/writing files and getting Chrome OS version.

BUG=chromium-os:17187
TEST=./tools.py chromeos-version

Change-Id: If5fc1870fcecc51a1c98b332159acfb39da84354
Reviewed-on: http://gerrit.chromium.org/gerrit/3981
Reviewed-by: Simon Glass <c00b0378376498bd9cd974c388df8854c0131d27@chromium.org>
Tested-by: Simon Glass <c00b0378376498bd9cd974c388df8854c0131d27@chromium.org>

coreos/dev-util,marineam/coreos-dev-util,mgireesh05/dev-util,coreos/dev-util,marineam/coreos-dev-util,mgireesh05/dev-util,coreos/dev-util,mgireesh05/dev-util