power: Add a link to power app in the system menu

Currently, the restart and shutdown functions accessible from the user drop down menu. There is no other way to reach these to functions. I propose that we bring back the icon in the system section.

• On Mobile interface, restart/shutdown items are hidden and not visible in the drop-down interface.
• It is not intuitive for a user to look for these functions in the user menu (except for some desktop interfaces combing that two areas). Having a power icon in the system page will help with this. Some interfaces like Roku and Routers actually place these two actions in the system section.