change info for old IEs

- adjust links to not only go to browserhappy, but also to the IE
update page directly
- adjust styling
- change css class name to get rid of 'chrome' as it has nothing to do
with it
remove content from index page

- move content into new 'about' page
- add info if JS is disabled + styling
update references and move one level up
fallback for svg logo
change bg to be fixed
change logo default format to svg
misc. updates

- remove import colors.less as already imported
- remove class 'chromeframe'
remove twitter
misc updates
update 404 page
misc updates