Added some Screenshots

I think, if you do something visual on github, you have to put screenshot in its readme. so here you are.

I don't know how to, but maybe you want to include the Github-Pages branch where the screenshots are stored: https://github.com/senfi/LaTeX-Template/tree/gh-pages
Or you do it on your own using the screenshots i did and this howto: https://help.github.com/articles/creating-project-pages-manually.