The sidebar in the admin site had grown pretty unweildy, including a lot

of information that really didn't need to be shown all of the time. This

change simplifies it a lot, eliminating the "System Information" box

completely and shrinking the width down to fit the content.
The one part of the System Information box which really still needed to

be linked was the security checklist, which has been added into the top

("System Settings") box and renamed as "Security Center".

Verified the appearance of the sidebar.