Add config up-to-date check script

Add a script that will determine if the sample config file is up to date
with the latest code in the source tree.  Running this automatically in
the gate will prevent patches from going in that didn't update the
sample config when they should have.

Change-Id: I3cdc3480a0947d78165172c1a720e7ef9c1fb144
Merge "Add config up-to-date check script"