Fix bugs in purge classes, cleanup

- OfflinePlayer objects were never mapped to names
- Essentials purge was run even if setting was disabled
- Console user saw messages twice
- Misc: trivial field reorderings, change DefaultPermission to be null safe
- Permissions: do not expose PermissionHandler just to get its type

src/main/java/fr/xephi/authme/permission/DefaultPermission.java

@@ -1,6 +1,5 @@
 package fr.xephi.authme.permission;
 
-import org.bukkit.Bukkit;
 import org.bukkit.command.CommandSender;
 
 /**
@@ -30,8 +29,8 @@ public enum DefaultPermission {
 
         @Override
         public boolean evaluateOffline(String name) {
-            // TODO Gnat008 20160617: Is this safe?
-            return Bukkit.getOfflinePlayer(name).isOp();
+            // TODO #784: Check if there is an elegant way to evaluate OP status
+            return false;
         }
     },
 

src/main/java/fr/xephi/authme/permission/PermissionsManager.java

@@ -217,12 +217,12 @@ public class PermissionsManager {
     }
 
     /**
-     * Get the current permissions system handler.
+     * Return the permissions system that is hooked into.
      *
-     * @return The permissions system handler.
+     * @return The permissions system, or null.
      */
-    public PermissionHandler getHandler() {
-        return handler;
+    public PermissionsSystemType getPermissionSystem() {
+        return isEnabled() ? handler.getPermissionSystem() : null;
     }
 
     /**