Added support for a physical button and led strip

[emouty]

Hello,

I have added :

• support for a physical button to control the light.
• support for a led strip using the rpi_ws281x library

I also did some refactoring in the __init__.py, so there might be some conflicts with other ongoing pull request.

Note: I haven't found why (might just be my Pi) but the board was stuck in BCM mode so i switch the GPIO mode to BCM

[gigibu5]

Thank you for your pull request. Saddly, I do not have any RGB strips at hand to test it. If you could resolve the confilcts (some stuff was merged) and send me a video of it working as well as some screenshots of the setting panel and user interface, I would be happy to merge it.

[gigibu5]

Also, please change the indentation from 4 spaces to a single tab.

[emouty]

I did the rebase on your repository, I also added the change of the light icon in the UI when you press the physical button to turn on and off the light. I will send you the video soon, I just need to finish some wiring on the printer before

[eloo]

@emouty you need to wrap button in this line and below (or in L96 and 108) with int()

otherwise an exception is thrown

octoprint.server.api - ERROR - Error calling SimpleApiPlugin octolight
Traceback (most recent call last):
  File "/home/pi/oprint/lib/python3.7/site-packages/octoprint/server/api/__init__.py", line 94, in pluginData
    response = api_plugin.on_api_get(request)
  File "/home/pi/oprint/lib/python3.7/site-packages/octoprint/util/__init__.py", line 1737, in wrapper
    return f(*args, **kwargs)
  File "/home/pi/oprint/lib/python3.7/site-packages/octoprint_octolight/__init__.py", line 108, in on_api_get
    self.enable_watch_button(self._settings.get([BUTTON_PIN]))
  File "/home/pi/oprint/lib/python3.7/site-packages/octoprint_octolight/__init__.py", line 128, in enable_watch_button
    GPIO.setup(button, GPIO.IN, pull_up_down=GPIO.PUD_UP)
ValueError: Channel must be an integer or list/tuple of integers

[eloo]

i've tested your PR and except the one bug it seems to work properly

(normal light pin and button, i have not tested the LED strip feature)

[eloo]

also here we need to wrap with int()