Rename and clean up static direcories.

- rename static subdirs to css and js
- move global static dir to core/static, changed
- move global templates dir to core/templates
- check comments and code style of all our own CSS and JS files
- minor changes related to the changes of template and static files
Merge pull request #1193 from emanuelschuetze/rename-static-files

Rename and clean up static directories.