[ENH] Do not compute QI2 if masked noise is 0
[ENH] Do not compute QI2 if masked noise is 0

Close #165

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