add getXpubRescanStatus() method to api wrapper

static/admin/lib/api-wrapper.js

@@ -110,6 +110,14 @@ const lib_api = {
     )
   },
 
+  /**
+   * Gets the status of a xpub rescan
+   */
+  getXpubRescanStatus: function(xpub) {
+    let uri = this.baseUri + '/xpub/' + xpub + '/import/status'
+    return this.sendGetUriEncoded(uri, {})
+  },
+
   /**
    * Notifies the server of the new HD account for tracking.
    */