Fix issues with RemoteAdmin admin_save_heightmap and admin_load_heightmap not working.

This is because they were wrongly looking for both regionid and region_id parameters in the same request.
Now only region_id is required (and recognized), regionid having been already deprecated for some time.
This is essentially Michelle Argus' patch from http://opensimulator.org/mantis/view.php?id=6737 but with tabs replaced with spaces.
Thanks!