[TASK] Allow installation of composer installers 1.2.x

The newer version of composer installers has extendend
features, but is fully backwards compatible and proven to work nicely
with TYPO3 6.2.

Resolves: #75423
Releases: 6.2
Change-Id: Iaa25df38a55cb0276931123b549f60b86d0c5088
Reviewed-on: https://review.typo3.org/47515


Reviewed-by: Mathias Brodala <mbrodala@pagemachine.de>
Tested-by: Mathias Brodala <mbrodala@pagemachine.de>
Reviewed-by: Wouter Wolters <typo3@wouterwolters.nl>
Tested-by: Wouter Wolters <typo3@wouterwolters.nl>
Reviewed-by: Helmut Hummel <helmut.hummel@typo3.org>
Tested-by: Helmut Hummel <helmut.hummel@typo3.org>