Adding `.editorconfig` file to standardize the structure of files, such as indentation and spaces.

For the `.editorconfig` work you need to install the plugin in the editor. 
On the official website there is a list of plugins: http://editorconfig.org/#download

```
# editorconfig.org

root = true

[*]
indent_style = space
indent_size = 2
end_of_line = lf
charset = utf-8
trim_trailing_whitespace = true
insert_final_newline = true
```