Refactor upload code
Create a file in the database only from one place.
Generate achievements from XML file.
Display achievements name in the user tab.
Add additional check when crating an addon.
Use one method in Addon class to check for the user permissions
Remove backward compatibility code, because we are going to start with a clean database.
Move .dtd files to assets directory
Renamed 'SITE_ROOT' to 'ROOT_LOCATION', to be consistent with the naming convention.
Add the possibility to use HTTPS.