Move common actions to a floating toolbar

[sebastianquek]

The common actions (print, share, download) aren't obvious as they are positioned in a place that users are unlikely to look at. For example, after scrolling down to verify the cert, I wouldn't be able to see the print button because it's now all the way at the top.

Perhaps we can have a toolbar that floats above the renderer, so when the user scrolls down, the toolbar will remain in view.

[Nebulis]

#472