Add new /gang vote and /gang callvote commands.

Signed-off-by: Staartvin <mijnleraar@msn.com>
Add new commands in help page.

Signed-off-by: Staartvin <mijnleraar@msn.com>
Added new methods for Gangs, such as:

- broadcasting for the gang
- calling or stopping an election
- checking whether a player has voted
- checking if there's an election running.

Signed-off-by: Staartvin <mijnleraar@msn.com>