message: show debug messages only if debug mode is enabled
diff: import { ILog } from './Log.interface'
  +import Client from '../Client';
  enum LogLevel {
  Debug,
  @@ -35,7 +36,11 @@ export class Logger implements ILog {
  }
  private log(level: LogLevel, message: string, ...data) {
  - if (/*Client.isDebugMode() && */ typeof console !== 'undefined') {
  + if (typeof console !== 'undefined') {
  + if (!Client.isDebugMode() && level === LogLevel.Debug) {
  + return;
  + }
  +
  let logFunction = (level === LogLevel.Warn || level === LogLevel.Error) ? 'warn' : 'log';
  console[logFunction].apply(this, [this.getPrefix(level) + message, ...data]);
  