Configuration and registry units

#### 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.