Check if the uploaded file really is an image.
Check if the uploaded file really is an image.

via http://breakthebit.org/post/77478059324/fixing-missingrequiredvalidatorerror-when


Former-commit-id: 3cfe15733fd2d3334a73650831381d2523e4f2ed
chaosdorf/mete,chaosdorf/mete,chaosdorf/mete,YtvwlD/mete,chaosdorf/mete,YtvwlD/mete,YtvwlD/mete,YtvwlD/mete