* PaddleRec release 1.6 api update

* Update README.md

* Update README.md

bold remind of paddle version

* Update README.md

change paddle version note

add xDeepFM, DCN model in PaddleRec/ctr.
change DeepFM data download script.

* add directory deepfm

* add code and data for deepfm

* 	modified:   README.md
	deleted:    picture/deepfm_result.pdf
	new file:   picture/deepfm_result.png

* 	modified:   README.md
	modified:   args.py
	modified:   data/download_preprocess.sh
	modified:   data/preprocess.py
	modified:   infer.py
	modified:   local_train.py

* 	modified:   README.md

* 	modified:   README.md

* 	modified:   README.md
	modified:   criteo_reader.py
	deleted:    data/aid_data/train_file_idx.pkl2
	new file:   data/aid_data/train_file_idx.txt
	modified:   data/download_preprocess.sh
	modified:   data/preprocess.py

* 	modified:   criteo_reader.py

* 	modified:   criteo_reader.py

* On branch deepfm
Changes to be committed:
	new file:   xdeepfm/README.md
	new file:   xdeepfm/args.py
	new file:   xdeepfm/criteo_reader.py
	new file:   xdeepfm/data/test_data/ev
	new file:   xdeepfm/data/train_data/tr
	new file:   xdeepfm/infer.py
	new file:   xdeepfm/local_train.py
	new file:   xdeepfm/network_conf.py

* On branch deepfm
Changes to be committed:
        modified:   README.md

*  On branch deepfm
 Changes to be committed:
	modified:   criteo_reader.py
	deleted:    data/aid_data/feat_dict_10.txt

* 	modified:   preprocess.py

* 	new file:   aid_data/feat_dict_10.pkl2

* 	modified:   data/preprocess.py

* 	modified:   README.md
	modified:   local_train.py

* 	modified:   local_train.py

* 	modified:   local_train.py

* 	modified:   local_train.py

*  On branch deepfm
 Changes to be committed:
	deleted:    xdeepfm/README.md
	deleted:    xdeepfm/args.py
	deleted:    xdeepfm/criteo_reader.py
	deleted:    xdeepfm/data/test_data/ev
	deleted:    xdeepfm/data/train_data/tr
	deleted:    xdeepfm/infer.py
	deleted:    xdeepfm/local_train.py
	deleted:    xdeepfm/network_conf.py