Use seaborn theming and color palettes

Now that we have seaborn integrated, we could perhaps use it within style to provide more features for the style context. I'm particularly thinking about the seaborn themes and seaborn color palettes.

We should however restrict ourselves to those features that can not be achieved via the matplotlib stylesheets; I have the feeling, that there is some overlap and seaborn "just" provides another way of setting the RC parameters.

This is not the case for the colour palettes, though: Setting the matplotlib property cycler by hand is really annoying and it would be a nice improvement to be able to set it via style using seaborn.