Fixes #553 OnNewLaunchParameters never getting called

[Zyhlon]

Super simple fix for OnNewLaunchParameters never getting called. Assuming InstallEvents was just forgotten in the SteamApps class. Guess not a lot of people are using that callback :P

Fixes #553

[compujuckel]

Just ran into the same bug with OnDlcInstalled, dirty hack for anyone waiting for this to be merged:

typeof(SteamApps).GetMethod("InstallEvents", BindingFlags.NonPublic | BindingFlags.Static).Invoke(null, null);