usrmgr: improve gui interface

This patch enhances the GUI of the User Manager Control Panel. It adds the "Add.../Remove/Properties" buttons found in the Windows 2000 version of the User Manager to both the Users and Groups tabs. This change makes it easier for newer users to manage the users and groups as it gives better visual indication of what to do. I even added the Check Box to determine if the computer requires a user name and password to log on every time you start it up.

And I even added a button for resetting the administrator password. In the original Windows 2000 User Manager, you notice that it the button is inside a group box with a text description telling the user to click the button to reset the administrator password. Personally, I see this as repetition of information that just takes up extra space. So, I have consolidated it to simply a lone button that says, "Reset Administrator Password" to hopefully simplify this. Just let me know if this somehow doesn't work or gets too confusing.