Remove Wordpress nag messages about upgrades

They make no sense in an UBOS context. How to:

• http://www.wprecipes.com/how-to-disable-the-please-update-now-message-in-wp-dashboard
• http://wpmu.org/daily-tip-how-to-disable-the-wordpress-update-notice/
• http://wordpress.stackexchange.com/questions/77148/remove-update-messages-for-deactivated-plugins