Don't update it if it isn't necessary.

Otherwise, the screen would flash everytime, regardless of the setting
set by the user. I'm keeping the code
there in case I or someone else find a fix.

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.