Layout inheritance doesn't work correcty

In `post.html` and `page.html`, the class is set to `'post-template'` and `'page-template'`, respectively. But in the output html of article (post) and page, the `` tag doesn't contain `post-template` or `page-template`, but contains `home-template`.

It looks like the inheritance of Jekyll doesn't work correctly, because Jasper theme code seems to be correct.
For example, `post.html` contains `class: 'post-template'`,

```
---
layout: default
disqus: false
class: 'post-template'
---
```

and any specific markdown post file (e.g., `1963-08-28-i-have-a-dream.md`) doesn't override any `class`.

```
---
layout: post
cover: 'assets/images/cover4.jpg'
navigation: True
title: I Have a Dream
date: 1963-08-28 10:18:00
tags: speeches
subclass: 'post tag-speeches'
logo: 'assets/images/ghost.png'
author: martin
categories: martin
---
```

I'm not familiar with Ruby and not fully sure this is the problem of Jasper theme or Jekyll core.

Temporarily I can use the `post-template` and `page-template` using `class` tag directly in the post markdown files like below, but I think it is not the fundamental solution.

```
---
layout: post
cover: 'assets/images/cover4.jpg'
navigation: True
title: I Have a Dream
date: 1963-08-28 10:18:00
tags: speeches
class: 'post-template'
subclass: 'post tag-speeches'
logo: 'assets/images/ghost.png'
author: martin
categories: martin
---
```

Please give me an advice.