Changed how configuration works.

Core will now require more libraries by default to setup required core classes:
 * Loader (ogel/loader)
 * Environment (ogel/environmenter)
 * ConfigurationManager (ogel/configurator)
 * Events (ogel/events)
 * Config (ogel/config)

To replace any of these classes with custom classes one must extend Core class and initialize it before bootstrap.php is included.

Core class responsibilities:
 * Loader - autoloader functionality
 * Environment - currently to specify environment manually - automatic environments are comming in future releases
 * ConfigurationManager - configuration file loading within config directories. Depends on Environment.
 * Events - provides event triggering and listening
 * Config - uses Events and ConfigurationManager to load configuration actions (previously known as Core configuration includes)

This change makes code more modular and easier to manage. Extra required libraries/core classes isn't a huge downside because it's still possible to replace them with custom versions.
Added structure for abstracter configuration.
Removed helper_function.php as there is no need for them now.
Merge branch 'abstract-configuration'