Add logging on bean creation and updating

Quite handy to have some logging when new beans are created or existing beans are updated. Attached patch adds this, in a very similar vain to the way node.module does it. It adds a watchdog notice and a drupal_set_message. It also adds a new public method to the bean core to enable to yo retrieve the human readable name of the bean's type. This was seemed to be the nicest way of getting at that information, in a way that is reusable.