模板中注入版本

@@ -9,7 +9,8 @@ let express = require('express'),
     path = require('path'),
     bodyParser = require('body-parser'),
     cookieParser = require('cookie-parser'),
-    favicon = require('serve-favicon');
+    favicon = require('serve-favicon'),
+    pkg = require('./package.json');
 
 require('express-handlebars');
 
@@ -18,6 +19,7 @@ let app = express();
 
 // 向模板注入变量
 app.locals.devEnv = app.get('env') === 'development';
+app.locals.version = pkg.version;
 
 app.set('view engine', '.hbs');