URBNG Applied the look and feel according to a specification given by the UX team - part 1

Changes:
 - CSS for main page (not complete)
 - CSS for games list
 - CSS for headers and navigation bar
 - CSS for game creator (not complete)
 - just a few new tests and updates for the old ones (will be more in next commit)

Graphics used must be changed in the future (for a better quality issue)