Config and Registry

#### Configuration unit meets the requirements of [issue](https://github.com/Baziak/php-education-2014/issues/1):
configs may have a block structure;
configs are written in php array;
there is a possibility to switch configs;
there is a possibility to merge configs.

#### Registry-unit has a possibilities:
get/set a registry value by key;
delete a registry element;
check if element exists;
lock/unlock element;
get a registry array with all elements.