Updated loadMetaData to search for metadata file using rom header. Added RomHeader.

I used the readBytes function to get basic info off the top of the rom commonly referred to at the rom header, thus named RomHeader. It contains information like the game code (four characters), the game short name, and the manufacturer id corresponding to GBA. Also I changed the loadMetaData function to refer to the rom short name for help finding the metadata file in the roms folder.
TODO: change roms folder from config