Fixes and language class

Hi!

I made small changes:
* config.php file was renamed config.example.php,
because the root is .gitignore that ignores the config.php file transfer during commit.

<b>For dev: It is only one note (!) To make sure everything was ok, create a new config.php file and leave config.example.php</b>

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When problems with this run

         git rm --cached app / core / config.php

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I added my language class is a little simpler, use is similar,
in constuctor when calling in as the second parameter, you can specify the language, eg:

         $this->language->load ('welcome', 'en');

then load file from:

          app/language/pl/welcome.php