append option headers to the index request

src/job.js

@@ -28,9 +28,7 @@ export default class Job extends events.EventEmitter {
 
     this.debug = (...msg) => debug(...msg, `id: ${this.id}`);
 
-    this.ready = createIndex(this.client, this.index, this.doctype)
-    .then(() => {
-      return this.client.index({
+    const indexParams = {
       index: this.index,
       type: this.doctype,
       id: this.id,
@@ -46,7 +44,13 @@ export default class Job extends events.EventEmitter {
         max_attempts: this.maxAttempts,
         status: contstants.JOB_STATUS_PENDING,
       }
-      })
+    };
+
+    if (options.headers) indexParams.headers = options.headers;
+
+    this.ready = createIndex(this.client, this.index, this.doctype)
+    .then(() => {
+      return this.client.index(indexParams)
       .then((doc) => {
         this.document = {
           id: doc._id,