making info api port configurable

conf/config.example

@@ -1,6 +1,7 @@
 {
   "interval": 1,
   "infoApi": true,
+  "infoApiPort": 9998,
   "jobs": {
     "yourSearchJob": {
       "notification": {

lib/api/api.js

@@ -1,7 +1,7 @@
 const bodyParser = require('body-parser');
 const config = require('../../conf/config');
 const { getLastJobExecution, getLastProviderExecution, getTotalNumberOfListings } = require('../services/store');
-const PORT = 9998;
+const PORT = config.infoApiPort || 9998;
 const service = require('restana')();
 const enabled = config.infoApi == null ? false : config.infoApi;