README: Remove paragraph about CSS

I've had a look at Compass and YAML, but they don't look like they would
be more helpful than confusing for a CSS beginner. Maybe I'm wrong, but
to me it seemed like I would be faster and more powerful by just
searching the CSS snippets I need on the web and using Garden to
manipulate them.
Restructure HTML templates slightly

 - I thought it might be better to have separate divs for the columns
   already in the wrapper template. So introduce them.

 - Correct the contact link.

 - Turn "Learn more" into "Try it out". – I think it's much more
   attractive for the user to be able to try out the system without
   signing up than just seeing some pictures and text.

 - Put an extra div around the main content in welcome.html, so that I
   can pull it out with Enlive more easily.
Adjust the deftemplates and defsnippets

In bc87d96 I had made an adjustment to the HTML. Change the Enlive code
to take advantage of that. That means putting the login form into the
right column and the main text in the middle.
Add some custom fonts to the design

This has to be considered further. See README.
Make the design a bit more palatable

Roughly put the elements in the right places. Very roughly. There are no
colours, yet.