Correct path to components.css

Fix failure to find components.css which was introduced in e1919c5
(#2513)

src/vector/index.js

@@ -30,7 +30,7 @@ require('babel-polyfill');
 
 // CSS requires: just putting them here for now as CSS is going to be
 // refactored "soon" anyway
-require('../build/components.css');
+require('../../build/components.css');
 require('gemini-scrollbar/gemini-scrollbar.css');
 require('gfm.css/gfm.css');
 require('highlight.js/styles/github.css');