Created by: Superjomn

• Add a verbose mode to print some basic information in the init phrase.

I0814 06:59:20.258909 18819 api_impl.cc:94] 
Inference Inputs:
 - title1
 - title2
 - title3
 - l1
I0814 06:59:20.258929 18819 api_impl.cc:101] 
Inference Outputs:
 - scale_0.tmp_0

• Add a helper header file paddle_inference_helper.h to release some helper function.