Fix bugs in app_test and example_test

[edieYoung]

1. made ipynb2py use nbconvert to convert ipynb to python instead of script
2. fixed bugs in run_apps_test, and revise the name of file "variatioanl-autoencoder" in notebook.
3. revised some path names in run_example_test

[edieYoung]

jerkins passed: http://172.168.2.101:8080/view/ZOO-PR/job/ZOO-PR-Python-AppTests/87/console

#1 anomaly-detection-nyc-taxi time used:41 seconds
#2 object-detection time used:5157 seconds
#3 ncf-explicit-feedback time used:197 seconds
#4 wide_n_deep time used:322 seconds
#5 using_variational_autoencoder_and_deep_feature_loss_to_generate_faces time used:724 seconds
#6 using_variational_autoencoder_to_generate_faces time used:446 seconds
#7 using_variational_autoencoder_to_generate_digital_numbers time used:257 seconds
#8 sentimentAnalysis time used:10442 seconds
#9 image-augmentation time used:145 seconds