added:
digital_sensor class
analog_sensor class
analog_temp_sensor class
unit tests

README instructions

Signed-off-by: Jonathan Galpin <jonathan@iqzero.net>
Merge branch 'master' of https://github.com/jonathan-galpin/php-denkovi-controller-interface

Conflicts:
	README.md

Signed-off-by: Jonathan Galpin <jonathan@iqzero.net>