Color coded the server browser and added a filter for password protected games

This implements #4495 and applies the color code style from www.openra.net/games/ with a legend:

![image](https://cloud.githubusercontent.com/assets/756669/5157404/c3e91e68-7309-11e4-9c5c-22fa5eface1e.png)

Essentially a followup of https://github.com/OpenRA/OpenRA/pull/6983 whose game name + "(Password)" was a little too subtle and unpolished for my taste.
An icon would probably be the most elegant solution, but again, why are you coming up with that here? The whole game is heavily relying on those colors. Sorry, but accessibility is not my personal priority nor has ever been in this project as far as I know.