Minor cosmetic changes.
Webserver: minor wording changes to the 404.html file.
Webserver: update web/default.css.

* Add normalize.css minified with `cleancss --s1 -b`
* Add box-sizing
* Remove float with display:inline
web/javascript.js: Fix a few JSHint warnings.
Update coverity.bat.

* the COVDIR variable can be set to specify the coverity dir
* use our build.bat as the coverity build command
* build release filters too