Bugfix/verloc fixes and adjustments (#618)

* Using new display trait for identity key

* Establishing verloc connection with timeout

* Further decrease in log severity

* Writing echo packets with timeout

* Sender formatting

* ConnectionWriteTimeout error definition

* Writing verloc results in chunks

* Added run started and run finished fields to verloc

* Reordered the fields

* Storing the timestamps as options to indicate run in progress

mixnode/src/node/mod.rs

@@ -144,6 +144,7 @@ impl MixNode {
         let config = rtt_measurement::ConfigBuilder::new()
             .listening_address(listening_address)
             .packets_per_node(self.config.get_measurement_packets_per_node())
+            .connection_timeout(self.config.get_measurement_connection_timeout())
             .packet_timeout(self.config.get_measurement_packet_timeout())
             .delay_between_packets(self.config.get_measurement_delay_between_packets())
             .tested_nodes_batch_size(self.config.get_measurement_tested_nodes_batch_size())