GC-703 update with HackMD editor

* ensure to update Page.hasDraftOnHackmd even if draft is outdated

lib/models/page.js

@@ -1352,12 +1352,7 @@ module.exports = function(crowi) {
    * @param {Boolean} newValue
    */
   pageSchema.statics.updateHasDraftOnHackmd = async function(pageData, newValue) {
-    const revisionIdStr = pageData.revision.toString();
-    const revisionHackmdSyncedIdStr = pageData.revisionHackmdSynced.toString();
-    if (revisionIdStr !== revisionHackmdSyncedIdStr) {
-      return;
-    }
-    else if (pageData.hasDraftOnHackmd === newValue) {
+    if (pageData.hasDraftOnHackmd === newValue) {
       // do nothing when hasDraftOnHackmd equals to newValue
       return;
     }