no reason to use a set here.
zPermissions: Fix setting of world-specific permissions.
  Give admins some degree of control over what's considered the "primary group."
  Decrease service priority.
Merge pull request #403 from ZerothAngel/master

Misc zPermissions fixes and changes
update pom for bukkit version
zPermissions: If chat prefix/suffix is unset, return empty string instead of null.
Merge pull request #406 from ZerothAngel/master

zPermissions: Return empty string instead of null when prefix/suffix is unset