Feature/2.05/change modle base class

Updated feature Made beforeSave and beforeDelete events of most models available for registration via the PluginManager
Dev changed inheritance of most Model Classes from CActiveRecord to LSActiveRecord

As Suggested to me on LS Forums i made a Pull Request for this changes: http://www.limesurvey.org/de/forum/development/94204-205-pluginevents-and-modelevents