Fix `yesod devel`, warnings, move js files

[jannschu]

• yesod devel working
• minor code formations
• use Settings.StaticFiles (intentional not used?)
• README update (yesod devel and db dump)
• compiler warnings (shadowing, types)
• move js files to static/js. Maybe images and css, too?

Have a look at it, my time spent with Haskell was short and a while ago.

Next I am going to try a few design tweaks.

[astro]

Thank you very much. It is plain great that this project brings you back to this awesome language!