Fix typo in object permission type name.

guacamole-ext/src/main/java/net/sourceforge/guacamole/net/auth/permission/ObjectPermission.java

@@ -71,7 +71,7 @@ public interface ObjectPermission<T> extends Permission<ObjectPermission.Type> {
         /**
          * Change who has access to an object.
          */
-        ADMINSTER
+        ADMINISTER
 
     }