[TYPO3-mvc] Switch storage backend in FE context

[Torsten Schrade]

> In a BE context this works absolutely fine. But strangely enough it 
> doesn't work for me in a FE context.

Ok, found it. The reason is: http://forge.typo3.org/issues/50788 and 
indeed I had a FLUIDTEMPLATE object on the very same page that 
interfered with the standard extbase bootstraping mechanism. Phew.

Cheers, Torsten