Fix incorrect address in connectvity check report:
The remoteAddress is the address as seen on the socket, which for
incoming connections has a random port chosen by the remote implementation
that is different from the port number used to accept connections by the
remote listening socket. The checkedAddress is the remote address as seen
on the socket, combined with the port advertised in the TMEndpoints message.
This fixes the reporting and metadata associated with addresses tested
for connectivity.

The README has been updated to reflect that uptime is no longer part of
the metadata associated with IP addresses saved for bootstrapping.