Cutting CNI volumes

[leotozzi88]

Calibration volumes are included in the CNI fMRI and DWI scans.
These include:

• 2 scans for fMRI
• 3 scans for SBRef
• 3 scans for Fieldmaps
• 2 scans for DWI

These should be cut before the images are processed. At the moment this step is embedded in the conversion script, eventually it should be a script that follows conversion but precedes processing.

[bstavel]

I agree. I think there should likely be a Bidsisfication script, followed by a validation script, where we check for the right number of volumes, and cut the dummy volumes