[TASK] Fix TYPO3 6.1+ compat, remove dependencies to EXT:fed

I made all the fixes for TYPO3 6.1+ and completely removed the dependencies to EXT:fed
Where I could find a fitting ViewHelper in current EXT:vhs, I used that one, where I couldn't, I copied the ViewHelper to EXT:notify. Furthermore I copied needed services from EXT:fed to EXT:notify.
If you plan to make 6.2 the minimum requirement then this class can be removed; `json_decode` can be called with these constants as needed, without caring if they are supported due to PHP version. Since 6.2 requires PHP 5.3 we can trust that these constants are supported, if that's the minimum required core version.