[TASK] Update readme copyright date to 2017

Releases: master,7.6
Resolves: #80645
Change-Id: I346a18f4f8983ee570bb5f0cae1e6635335f7d73
Reviewed-on: https://review.typo3.org/52324


Reviewed-by: Benni Mack <benni@typo3.org>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Jan Helke <typo3@helke.de>
Tested-by: Jan Helke <typo3@helke.de>
Reviewed-by: Riccardo De Contardi <erredeco@gmail.com>
Tested-by: Riccardo De Contardi <erredeco@gmail.com>
Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>