Add helper to get translated configuration values
Add helper to get translated configuration values

This will be used to get the proper translation for configuration values
like:

- Title
- Subtitle
- Description

This translations should be located in the `_data` folder of the Hexo
site, in files named like `config_<lang>.yml`.

Built from affa6376e67ab427d3294cf1e068b6d5ce303366.

ahaasler/hexo-theme-colos,ahaasler/hexo-theme-colos