changed the number of iteration of test_lenet_* to have a minimum of .1s of GPU time (to have more stable speed up number) and a maximum of 10s of cpu time(to don't be too long).

fix ignore_error=True by using the requested batch_size and print the time executed and print the result at each iter.

added possibility to ignore_errors in run_test_conv_nnet2_classif to benchmark even broken implementations.

that the opwiseclinker is efficient even for relatively small networks.