[bunyan] add levelFromName and nameFromLevel

types/bunyan/bunyan-tests.ts

@@ -129,3 +129,6 @@ class MyLogger extends Logger {
         super(options);
     }
 }
+
+const nameLevel: number = Logger.levelFromName['warn'];
+const levelName: string = Logger.nameFromLevel[10];

types/bunyan/index.d.ts

@@ -210,6 +210,9 @@ declare namespace Logger {
     const ERROR: number;
     const FATAL: number;
 
+    const levelFromName: { [name: string]: number };
+    const nameFromLevel: { [level: number]: string };
+
     type LogLevel = 'trace' | 'debug' | 'info' | 'warn' | 'error' | 'fatal' | number;
 
     const stdSerializers: StdSerializers;