[TASK] Add download button

Resolves: #61240
Releases: 3.0
Change-Id: I2030cb60e0b25b709ff8431d20337c41a0710fa9
Reviewed-on: http://review.typo3.org/32472
Reviewed-by: Fabien Udriot <fabien.udriot@ecodev.ch>
Tested-by: Fabien Udriot <fabien.udriot@ecodev.ch>