add permission check for storage path

app/Providers/BootServiceProvider.php

@@ -28,6 +28,11 @@ class BootServiceProvider extends ServiceProvider
             throw new PrettyPageException(trans('setup.file.no-dot-env'), -1);
         }
 
+        // check permissions of storage path
+        if (!is_writable(storage_path())) {
+            throw new PrettyPageException(trans('setup.permissions.storage'), -1);
+        }
+
         try {
             // check database config
             Database::prepareConnection();

resources/lang/en/setup.yml

@@ -0,0 +1,9 @@
+database:
+  connection-error: Unable to connect to MySQL server, please check your configuration. :msg
+
+file:
+  permission-error: Unable to create textures folder, please check the directory permissions or place one manually.
+  no-dot-env: Unable to find the .env configuration file.
+
+permissions:
+  storage: Unable to write to storage directory, please check the permissions.

resources/lang/zh-CN/setup.yml

@@ -4,3 +4,6 @@ database:
 file:
   permission-error: textures 文件夹创建失败，请确认目录权限是否正确，或者手动放置一个。
   no-dot-env: 找不到 .env 配置文件
+
+permissions:
+  storage: 无法写入 storage 目录，请检查目录权限是否正确