Fixing undefined index notice in DevTemplateEngineRenderer

| Q             | A
| ------------- | ---
| Bug fix?      | [yes]
| New feature?  | [no]
| BC breaks?    | [no]
| Deprecations? | [no]
| Tests pass?   | -
| Fixed tickets | -
| License       | The BSD 3-Clause License
| Doc PR        | -

http://0.0.0.0:8080/dev/resource/ へのアクセスで以下の E_NOTICE が発生します。

```console
...
[Sat Jun 14 17:58:42 2014] E_NOTICE: Undefined index: halo in /path/to/project/src/Provide/ResourceView/DevTemplateEngineRenderer.php on line 155
[Sat Jun 14 17:58:42 2014] E_NOTICE: Undefined index: halo in /path/to/project/src/Provide/ResourceView/DevTemplateEngineRenderer.php on line 155
[Sat Jun 14 17:58:42 2014] E_NOTICE: Undefined index: halo in /path/to/project/src/Provide/ResourceView/DevTemplateEngineRenderer.php on line 156
[Sat Jun 14 17:58:43 2014] E_NOTICE: Undefined index: halo in /path/to/project/src/Provide/ResourceView/DevTemplateEngineRenderer.php on line 155
[Sat Jun 14 17:58:43 2014] E_NOTICE: Undefined index: halo in /path/to/project/src/Provide/ResourceView/DevTemplateEngineRenderer.php on line 155
[Sat Jun 14 17:58:43 2014] E_NOTICE: Undefined index: halo in /path/to/project/src/Provide/ResourceView/DevTemplateEngineRenderer.php on line 156
[Sat Jun 14 17:58:44 2014] E_NOTICE: Undefined index: halo in /path/to/project/src/Provide/ResourceView/DevTemplateEngineRenderer.php on line 155
[Sat Jun 14 17:58:44 2014] E_NOTICE: Undefined index: halo in /path/to/project/src/Provide/ResourceView/DevTemplateEngineRenderer.php on line 155
[Sat Jun 14 17:58:44 2014] E_NOTICE: Undefined index: halo in /path/to/project/src/Provide/ResourceView/DevTemplateEngineRenderer.php on line 156
...
```