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.
Started, password-protected games now have the yellow colour for a started game, but the text still says "password protected". You need the check for the `WaitingPlayers` state here as well.

![6993_1](https://cloud.githubusercontent.com/assets/4331210/5288804/a6dd9402-7b38-11e4-9554-d8cba0a9ee94.png)