logger fixes (#1244)

* logger: fix race conditions

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

* restore util/log for compatibility

Signed-off-by: Vasiliy Tolstov <v.tolstov@unistack.org>

util/log/README.md

@@ -0,0 +1,17 @@
+# Log
+
+DEPRECATED: use github.com/micro/go-micro/v2/logger interface
+
+This is the global logger for all micro based libraries.
+
+## Set Logger
+
+Set the logger for micro libraries
+
+```go
+// import go-micro/util/log
+import "github.com/micro/go-micro/util/log"
+
+// SetLogger expects github.com/micro/go-micro/debug/log.Log interface
+log.SetLogger(mylogger)
+```