- update: Bootstrap version to v4.0.0-beta.2

- update: vue-chartjs version to 3.0.0
- refactor: Remove old SCSS variables
- refactor: Breadcrumb Menu styles
- fix: External links issue
- fix: Mobile sidebar-nav height issue

Vue_Starter/scss/bootstrap/_close.scss

@@ -19,11 +19,11 @@
 // If you want the anchor version, it requires `href="#"`.
 // See https://developer.mozilla.org/en-US/docs/Web/Events/click#Safari_Mobile
 
-// scss-lint:disable QualifyingElement
+// stylelint-disable property-no-vendor-prefix, selector-no-qualifying-type
 button.close {
   padding: 0;
   background: transparent;
   border: 0;
   -webkit-appearance: none;
 }
-// scss-lint:enable QualifyingElement
+// stylelint-enable