* fix reader, metrics, frameworks to increase universality of PaddleVideo

* change config files from .txt to .yaml

* fix input to use PyReader and modify on readme to fit new codes

* adjust code structure and modify configs and readme to fit standard

* modify links of pdparams in readme and scripts

* fix pickle.dump in python3 and modify on readme of attention_lstm

* add description of weights argument in eval/predict/inference_model.py

update readme

* add_license for PaddleCV

* update license date

* update GAN license date

* add cuda check to show errors when run on paddle compiled with cpu only

* change use_cuda to use_gpu in the error infomation to be consistent with code

fix pickle.load to fit both python3 and 2

* add readme for ctcn metrics calculation

* fix code format in metrics/detections/README.md

* fix code format and add ``` in code lines

* fix description of video in models/readme to be same as PaddleVideo/readme
* add c2d and i3d backbone in nonloal/readme
* fix table format of nonlocal/readme