More efficient network usage

[s-crypt]

I have noticed that the PrusaLink on my Pi 3B+ uses ~10GB/day of upload, seemingly uploading the screenshots to be viewable from connect.

I think it would benefit both Prusa's and users' bandwidth to only refresh the images when a user is actively viewing connect, regardless of the refresh frequency set.
Viewing the page on PrusaLink should always be available locally, just limiting uploading when it is not necessary.