Report relays that sbws wants to test, but the test doesn't work

We should count:

• the number of times sbws tries to test a relay
• the number of times the test works and fails

If there is a high number of failures, we should also count:

• the number of times that pair selection works and fails
• the number of times that connecting works and fails
  • if there are a lot of these, count the hop that fails
• the number of times that data transfer works and fails