fix 在css的url中的路径问题

Author: Ma63d

build/utils.js

@@ -28,7 +28,9 @@ exports.cssLoaders = function (options) {
     // Extract CSS when that option is specified
     // (which is the case during production build)
     if (options.extract) {
-      return ExtractTextPlugin.extract('vue-style-loader', sourceLoader)
+      return ExtractTextPlugin.extract('vue-style-loader', sourceLoader,{
+        publicPath:'../../'
+      })
     } else {
       return ['vue-style-loader', sourceLoader].join('!')
     }