Adding support for 1wire sensors DS18S20 and co (#80)

* Create ds18b.py

* Update and rename pi_mqtt_gpio/module/ds18b.py to pi_mqtt_gpio/modules/ds18b.py

* testing DS18B

* add config example

* Update README.md

Adding ds18b sensor module documentation and example.

* Update README.md

* Delete server.py

* accidently deleted server.py

* fix after testing

Co-authored-by: Ellis Percival <github.com@failcode.co.uk>