Install optional movies and scores from CD

So not finished just yet, but its working for the allies and soviet CDs.

Just looking for feedback and such to make sure im not doing anything terribly wrong (yes i realize the menu logic .cs file is named wrong).

What it does is let the user select a CD which they can install movie files and additional scores from, checks the disc based on a SHA1, installs the required content. Doing this in the main menu causes it to freeze and then speed up once the hash is obtained from the disc and the files are copied. If this is all looking good we should look at where the buttons and things should go, and i'll work on trying to get the scores from the expansions which so far seems to conflict with the scores.mix file included in the base game.