Color/style attribute on features

[perrygeo]

@sfletche has done some preliminary work on this with a color picker to set the KML color. We'd have to think about how to make this a core part of all features. Lots to consider here (how to make it work in 2D vs 3D, widgets, what format to store style info in?, how it can be customized or turned off...)

Especially as we move towards geojson (which will require external styling to be applied to features), we should think of a way to store styling info in with database.