[FIX] Fixes X-axis flip in mosaics
[FIX] Fixes X-axis flip in mosaics

Since image orientation is RAS, the X-axis is represented flipped (Right-to-left).
This PR fixes #229

oesteban/mriqc,poldracklab/mriqc,poldracklab/mriqc,oesteban/mriqc,poldracklab/mriqc,poldracklab/mriqc,oesteban/mriqc,oesteban/mriqc