MAINT: Bump to 3.7+

[mgxd]

also removes a python 2 test of the docker wrapper, and bumps licenses up a year

[auto-comment]

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[effigies]

This is intentionally left available in Python 2 because Python 2 is still the default Python on a lot of systems, and so it's the cheapest way to get people going in Docker.

[effigies]

Please also adjust:

https://github.com/poldracklab/fmriprep/blob/2cf3e494b3921f9b9549e6caa686a737bc28d118/setup.cfg#L21

https://github.com/poldracklab/fmriprep/blob/2cf3e494b3921f9b9549e6caa686a737bc28d118/setup.cfg#L16-L18

https://github.com/poldracklab/fmriprep/blob/2cf3e494b3921f9b9549e6caa686a737bc28d118/.travis.yml#L9