Created by: qingqing01

It needs to copy the protostr file manually after generating test_xx.protostr.unittest when add a new unit test for trainer_config_helpers now. For example, the test_pad.protostr.unittest will be generated after running:

./python/paddle/trainer_config_helpers/tests/configs/generate_protostr.sh python_path

Then:

cp python/paddle/trainer_config_helpers/tests/configs/protostr/test_pad.protostr.unittest python/paddle/trainer_config_helpers/tests/configs/protostr/test_pad.protostr

This PR is used to generate protostr automatically when running the unit test. For example

make test ARGS="-R test_layerHelpers -V"