I'm not sure. If you look at this website, it says that the green kit is the away kit.
It seems to be official, because there's a link to it from Hannover 96's german site. (Click the UK flag in the top right)
There was/is a massive fire at a fuel depot.. Look at this satellite image:
The huge amount of smoke produced by the fire is indicated by the black and grey area to the south of the depot
visible on this UK satellite image taken a few hours after the blast.