Introduce different log levels

modules/utils/logging.js

@@ -0,0 +1,24 @@
+const log = console.log.bind(console);
+
+function noop() {}
+
+let debug, info, warn;
+
+if (process.env.LOG_LEVEL === "none") {
+  debug = info = warn = noop;
+} else if (process.env.LOG_LEVEL === "debug") {
+  debug = info = warn = log;
+} else if (process.env.LOG_LEVEL === "warn") {
+  debug = info = noop;
+  warn = log;
+} else {
+  // default LOG_LEVEL = "info"
+  debug = noop;
+  info = warn = log;
+}
+
+module.exports = {
+  debug,
+  info,
+  warn
+};