Put each log file in a folder

The filesystem was struggling.  If the path has a trailing /, then put
everything inside the folder.  Otherwise, use that as the base name and
append.

Change-Id: I042e4886989724c5e179fe81b3017a695cbfd016
diff --git a/aos/events/logging/logger_main.cc b/aos/events/logging/logger_main.cc
index 1d0c55e..1bc74f2 100644
--- a/aos/events/logging/logger_main.cc
+++ b/aos/events/logging/logger_main.cc
@@ -28,8 +28,8 @@
         aos::logging::GetLogName("fbs_log"), event_loop.node());
   } else {
     log_namer = std::make_unique<aos::logger::MultiNodeLogNamer>(
-        aos::logging::GetLogName("fbs_log"), event_loop.configuration(),
-        event_loop.node());
+        absl::StrCat(aos::logging::GetLogName("fbs_log"), "/"),
+        event_loop.configuration(), event_loop.node());
   }
 
   aos::logger::Logger logger(&event_loop);