New commands:
- cjm set firstjoinmessage <message > - Sets the first join message
- cjm set joinmessage <message> - Sets the join message
- cjm set privatefirstjoinmessage <message> - Sets the private join message
- cjm set privatejoinmessage <message> - Sets the private join message
- cjm set quitjoinmessage <message> - Sets the quit message
Note: The commands do support color and formatting codes such as &a or &o