message: grpc: re-use LogInfo/Err from log.h
diff: #include <grpc++/security/server_credentials.h>
  #include "dronecore.h"
  +#include "log.h"
  #include "dronecore.grpc.pb.h"
  #include "action/actionrpc_impl.h"
  #include "mission/missionrpc_impl.h"
  @@ -51,7 +52,7 @@ void RunServer()
  std::fstream file;
  file.open("grpc/proto/plugins.conf");
  if (!file) {
  - std::cout << "Error in reading conf file" << std::endl;
  + LogErr() << "Error in reading conf file";
  return;
  }
  std::vector<::grpc::Service *> list;
  @@ -65,19 +66,18 @@ ${PLUGIN_MAP_APPEND_STRING}
  bool discovered_device = false;
  DroneCore::ConnectionResult connection_result = dc.add_udp_connection();
  if (connection_result != DroneCore::ConnectionResult::SUCCESS) {
  - std::cout << "Connection failed: " << DroneCore::connection_result_str(
  - connection_result) << std::endl;
  + LogErr() << "Connection failed: " << DroneCore::connection_result_str(connection_result);
  return;
  }
  - std::cout << "Waiting to discover device..." << std::endl;
  + LogInfo() << "Waiting to discover device...";
  dc.register_on_discover([&discovered_device](uint64_t uuid) {
  - std::cout << "Discovered device with UUID: " << uuid << std::endl;
  + LogInfo() << "Discovered device with UUID: " << uuid;
  discovered_device = true;
  });
  // We usually receive heartbeats at 1Hz, therefore we should find a device after around 2 seconds.
  std::this_thread::sleep_for(std::chrono::seconds(2));
  if (!discovered_device) {
  - std::cout << "No device found, exiting." << std::endl;
  + LogErr() << "No device found, exiting.";
  return;
  }
  @@ -88,7 +88,7 @@ ${PLUGIN_MAP_APPEND_STRING}
  builder.RegisterService(plugin_service);
  }
  std::unique_ptr<Server> server(builder.BuildAndStart());
  - std::cout << "Server listening on " << server_address << std::endl;
  + LogInfo() << "Server listening on " << server_address;
  server->Wait();
  }
  