retry of pwm.set_pwm on first exception due to I2C timing errors

add arg for custom figure format (e.g. 'png', 'pdf', 'svg' ...) for train.py

check TensorFlow version before overriding keras session

Small performance improvement and jitter output in ms

Improve performance by replacing division /255 with multiplications and adding some pep-8 formatting. Also fixing jitter output to be in ms

Update get_driving.md

Update Ip-Adress change to Hostname

Dev

* unrolling the salient method in keras-vis into 2 parts
* putting the optimizer which can be kept static into the initialization
* also remove unused code and imports