(feat): Allow transports to ignore .

Transports which do not supply   will process all log events.

src/Logger.ts

@@ -12,7 +12,7 @@ export class Logger {
     const tasks: Promise<void>[] = [];
 
     for (const transport of this.transports) {
-      if (level >= transport.minLevel) {
+      if (!transport.minLevel || level >= transport.minLevel) {
         tasks.push(transport.log(level, module, content));
       }
     }

src/typings/Transport.ts

@@ -1,7 +1,7 @@
 import LogLevel from './LogLevel';
 
 interface Transport {
-  minLevel: LogLevel;
+  minLevel?: LogLevel;
   log(level: LogLevel, module: string, content: string): Promise<void>;
 }