Add team-based permission requirement

Created by request of Zacraft210 on the Warhub server. 
This adds a team default permission configuration option. Default is war.player. It is modifiable at the zone level and the team level.
You could use this for example to make a mob fighting zone. The team for admins who would be spawning mobs would require a permission only admins had to be able to join it.
This could also be used to restrict a zone to a certain rank only and not allow higher ranked players in. The permission for the zone could be set to say, zone.bootcamp. The rank that you want to allow in could be granted that permission, and then other ranks and up (via permissions plugin group inheritance) could have that permission set to false so they could not join. Admins could be granted the permission to allow them to moderate the zone