Include last tag when tags option is all

Author: alexcanessa

lib/src/Gren.js

@@ -865,7 +865,7 @@ class Gren {
         const range = 2;
         const sortedReleaseDates = this._sortReleasesByDate(releaseDates);
 
-        if (sortedReleaseDates.length === 1 || this.options.tags === 'all') {
+        if (sortedReleaseDates.length === 1 || this.options.tags.indexOf('all') >= 0) {
             sortedReleaseDates.push({
                 id: 0,
                 date: new Date(0)