Travis update

black - The uncompromising Python code formatter.
https://github.com/psf/black
It requires python 3.6 or newer, though

* Add stages for makrdownlint, yamllint, mkdocs
* Update travis config so that it no longer generates warnings if pasted
  into https://config.travis-ci.com/explore
* Speed up linting phase (skip install)
* Move docs build earlier
* Allow yamllint and makrdownlint to fail

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