fix recursion bug, more friendly checkpoint reload (#495)
fix recursion bug, more friendly checkpoint reload (#495)

The checkpoint function used to fail if it was not
given a checkpoint that TF can recognize, becase
tf.train.latest_checkpoint returned None.  Now,
if that happens, assume they already gave us the
full checkpoint and just try using it
dpressel/baseline,dpressel/baseline,dpressel/baseline,dpressel/baseline