[WIP] Use different base image containing MCR

[octomike]

I am in the process of cleaning up the base MCR image a little bit, so you can directly base this image on it. Or is there a reason why you based it on bids_validator except that the MCR image is out of date?

[gllmflndn]

Thanks @octomike, I hadn't realised that the base_validator image was out of date and unmaintained. I don't think the base_MCR image existed at the time the SPM BIDS App was created and it might actually be inspired from it.
An application compiled with the MATLAB Compiler is tied to a specific version of the MATLAB Runtime so it is not necessarily changing that often. Let's continue the discussion on your pull request in base_MCR.