Allow setting colorList / template on a graph

[BradWhittington]

Hi, Thanks for the great project. I would love to see the colorList/template property supported, which would allow specifying, per graph/target the colours to use. When using it directly you can specify a colorList directly after the target in the url, and it will cycle through those colours instead of the default. 'template' also lets you use a predefined set of colours from graphite.

[ripienaar]

should be pretty simple, though not sure I'll have time to get to it anytime soon :(