Features/authors

## Improving style about site and gravatar support

- [x]  Adding authors module
- [x]  Showing outhors names within every post
- [x]  Showing gravatar image to every post
- [x] Hide some post without using

![support_for_gravatar](https://cloud.githubusercontent.com/assets/410885/4432199/c1f79de2-468a-11e4-9107-e9df15aa8d4f.png)