Feature/material design reol 72

What are the rationale behind this change? All i have ever heard is to avoid using the textual representations of colors.
See point number 5 on http://sixrevisions.com/css/12-common-css-mistakes-web-developers-make/
I see that black/white should always be #FFF and #000, but for consistency i do not think we should use the textual color representations at all