Small cosmetic change in admin screen: move submit buttons

In the admin screen, the 'Save configuration' and 'Reset to defaults' are form-wide buttons and should appear at the far bottom. However they are placed within your 'buttons' fieldset. (Collapse that group; you'll see an unwanted side effect :) )

That's because system_settings_form() uses a fieldset named 'buttons' too. Simple solution: rename your own fieldset. No further changes necessary.