Demoinfo detects L4D2 Branch as csgo demos

[Traderain]

Make a method or a check to detect if it is actually a csgo demo because it tries to parse:

• Alien Swarm
• Portal 2
• L4D2 demo but failes.

[Calak]

Here a pull request to catch this, but it must be checked cause i edited it from my smartphone.

Or you can manualy make the test I added.