Renamed the main system class to Sweia
Added classes and interfaces folders to the site folder to contain classes and interfaces specific to a specific site
Added an autoloader function for interfaces
Added a folder for Sweia Exceptions

Added a description to the includes folder

Updated the Sweia class
Removed the use of the global $DB variable

Sweia
- Made this class the entire system registry class
- Added database access through this class
Merge origin/master