Config option to set which color code prefix should be used.

1st commit is in case someone wishes to use a different chat system, like herochat (if you use chat listeners both on bukkit and forge side, message duplication may occur. I had that happen when glacy staff chat was used together with mytown)

2nd commit is for changing the color code prefix, from the default "$" alpha made, to anything the user desires (usually "&" to work with bukkit though)