Add Support for PSR-4 in TYPO3FlowInstaller

This pull-request adds the support for the PSR-4 standard to the TYPO3FlowInstaller.
Without this the resulting directory name under which PSR-4 packages are installed
have an incompatible name which the TYPO3 Flow packageManager doesn't understand

Related TYPO3.Flow Change: https://review.typo3.org/28097