add gzip configuration

lib/nuxt.js

@@ -41,7 +41,9 @@ class Nuxt {
         scrollBehavior: null
       },
       performance: {
-        gzip: true,
+        gzip: {
+          threshold: 0
+        },
         prefetch: true
       },
       build: {}
@@ -73,10 +75,8 @@ class Nuxt {
       maxAge: (this.dev ? 0 : '1y') // 1 year in production
     }))
     // gzip for production
-    if (!this.dev) {
-      this.gzipMiddleware = pify(compression({
-        threshold: 0
-      }))
+    if (!this.dev && this.options.performance.gzip) {
+      this.gzipMiddleware = pify(compression(this.options.performance.gzip))
     }
     // Add this.Server Class
     this.Server = Server

lib/render.js

@@ -31,7 +31,7 @@ export function render (req, res) {
       yield self.webpackDevMiddleware(req, res)
       yield self.webpackHotMiddleware(req, res)
     }
-    if (!self.dev && self.options.performance.gzip === true) {
+    if (!self.dev && self.options.performance.gzip) {
       yield self.gzipMiddleware(req, res)
     }
     // If base in req.url, remove it for the middleware and vue-router