#950 Add unregister by name to API

- Add method to API
- Ensure that unregistering in datasource is case-insensitive

src/main/java/fr/xephi/authme/api/NewAPI.java

@@ -221,6 +221,15 @@ public class NewAPI {
         management.performUnregisterByAdmin(null, player.getName(), player);
     }
 
+    /**
+     * Unregister a player from AuthMe by name.
+     *
+     * @param name the name of the player (case-insensitive)
+     */
+    public void forceUnregister(String name) {
+        management.performUnregisterByAdmin(null, name, Bukkit.getPlayer(name));
+    }
+
     /**
      * Get all the registered names (lowercase)
      *