Added character encoding to configuration which is used for rendering.

Hi, I've updated app to support character encoding configuration for rendering. It's helpful when you render pages with special characters and default locale on OS does not met your requirements. In such cases rendered pages contain odd characters (e.g. question marks) instead of required characters (e.g. čřžý). See attached picture:

![result](https://f.cloud.github.com/assets/352668/1556012/ee15c144-4ea4-11e3-96ff-26d89d77c387.png)

To set character encoding for app you have to change it in configuration file of application. As default encoding I've set UTF-8. If you decide to accept this pull request, please mention this configuration option in "Getting started".

Encoding is applied for page/post rendering and also for template rendering.

Hope this will be helpful :)