Add Config::get default value in case the configuration value does not exist

It wasn't documented by actually if a configuration is not find in the config file you can set a default value (just like a nice fallback 

Ex:

<code>Config::get('myfile.rows_per_page',25);</code>

In this case if I don't have myfile.php in the configuration directory or the rows_per_page array key define in it Config::get will still return 25