Update Keras.md as suggested by Pull Request #301
Update Keras.md as suggested by Pull Request #301

As suggested by https://github.com/googlecreativelab/teachablemachine-community/pull/301, Defined class_names, added end='' for print class (line 43) since using readlines() for labels.txt adds an extra line between class and confidence score.
Added compile=False since the model is already trained. Fixed a couple of syntax (e.g. #301 is missing some things in line 7)
googlecreativelab/teachablemachine-community,googlecreativelab/teachablemachine-community,googlecreativelab/teachablemachine-community,googlecreativelab/teachablemachine-community,googlecreativelab/teachablemachine-community,googlecreativelab/teachablemachine-community,googlecreativelab/teachablemachine-community