Addition of Meta Theme Colour Markup

Added suggested meta tag: For Colour Bleed/theme colour on Chrome UI on
Android (inline with current colour bleed trends, such as Yosemite/iOS8
etc).
@mrwigster Can you add [this link](http://updates.html5rocks.com/2014/11/Support-for-theme-color-in-Chrome-39-for-Android) here? Thanks!