Tobi adjustments

This PR is not necessarily to be merged, don't want to mess with your presentation, but it is for you to see what kinds of adjustments I make (added own config to not mess with what Jason is doing/merge
  conflicts/we will see) :)

One improvement I made (except for setup like ruby-* files and Gemfiles) ,center_vertically is new, there for centering the images - that way they work on all resolutions :)

Maybe at some point we can cherry pick changes or whatever from here.

I hade hoped just to make another config file, rearranging the slides and leaving slides out to my liking, that only works with named slides, though ^^