added dependencies

vendor/twbs/bootstrap/build/postcss.config.js

@@ -0,0 +1,18 @@
+'use strict'
+
+module.exports = ctx => {
+  return {
+    map: ctx.file.dirname.includes('examples') ?
+      false :
+      {
+        inline: false,
+        annotation: true,
+        sourcesContent: true
+      },
+    plugins: {
+      autoprefixer: {
+        cascade: false
+      }
+    }
+  }
+}