Gutenberg-related services (e.g., 'Online library') will now show an error message if they can't connect to the Internet and refuse to launch.

When an user first opened an ePUB, then a PDF, it didn't work. This was
due to an issue with the two tmpfs at '/kobo/inkbox' and '/kobo/run'.
This commit fixes that issue.

On this device, the Quit button makes the UI go beyond the limits of the screen when the menu bar is shown. Thus, the user will have to resort on the default Quit button found in MainWindow.

Inter is still there in a lot of areas and blends quite well with this new font.

Otherwise, we get some memory issues ...