cros_workon: move from src/scripts
cros_workon: move from src/scripts

BUG=11507
TEST=none

Change-Id: Id707179940cfe5aa7a51e6930d383924287d2d7f

Review URL: http://codereview.chromium.org/6312053

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