#292: Customizable series colors

#292 
In `ng_highchart.js` we have a list of colors we use for our charts. Please use the same (and of course, you can sue the constant to define this list and reuse it in `ng_highchart.js`).

If think this color list if preferable, we can try it out. But we need to make sure it's the same list in both places.