BUG - GHOSTBLOCK in studio/banners/prices

Tested with events module. After deleting the events mod and reinstallation of it, the ''old'' banner blocks created for the event module pages in studio/banner/prices were not deleted together with the uninstallation of the event module.

Result: 

• New banner blocks on same pages in studio/banner/blocks are denied with message ''block allready exists''
• ''Old Banners'' of these banner blocks are homeless and still listed in banner administration, they would need some kind of relocation button.
• Creating of similar types in studio/banner/types is not possible, message ''type allready exist''