Redesign "Stop after error" feature

[mastacheata]

Currently when the plugin encounters an HTTP error code it will disable the offending network completely and requires further action by the user.
This should probably be redesigned to use some kind of truncated exponential backoff algorithm and/or handle different errors with individual approaches. (i.e.: "You're way too high-frequent error" should still disable the plugin completely, but other errors should be retried after some time)