Show notification only when something is wrong

[jkufner]

When everything works there is no need to bother a user with notifications. Show notifications only when something is really wrong.

Examples:

• Photos successfully uploaded -> no notification.
• Phone has no connectivity, photos are enqueued for upload -> no notification.
• Connectivity is available, but server is not responding -> try again silently and notify when it fails few times in a row.
• There was errors, but now it looks ok -> remove old notification, no need to disturb the user.
• Connection to server is ok, but server returns garbage -> warn user about bad setup.
• Connectivity available, but upload failed due to lost connection -> no notification, just try again later.