Reset Pulse for newer WS2812B

[sGoehner]

Hi,

I just implemented a control for the WS2812B LEDs based on Your tutorial (thanks btw. it was very helpful :)). At first I could not make the WS2812B LEDs work and therefore did a bit of research. It turned out that the specification changed for newer models of the LEDs. Especially the reset pulse is now required to take at least 280 us. Check out: http://www.world-semi.com/Certifications/WS2812B.html for the newest datasheet. With an adjustment of the reset pulse duration the LEDs light up now. Hope that helps anyone.

[MaJerle]

Thats a good point. Can you make a pull request with changes?