Added the Options Menu with Volume Controls

-Added the volume control sliders for master, sfx and bgm volumes to the
option screen class.
-Also added 3 public float variables in the Game.java class for volume
control.
-Changed the P2 sign in the character screen to Blue.
-Removed the Character Selection Music from the SoundFiles.java class
since it should belong to the music class and not the sound class.
-Modified the button.png, button.pack and optionsMenuBG.png files