Support for GE data

[tsalo]

Several projects in the department acquire data at the UM scanner, which is a GE. I haven't checked heudiconv on GE data lately, but the last time I checked it still wasn't working properly. We modified a branch of heudiconv to work with GE dicoms, so we could include that in the Dockerfile and switch between versions in the code.

Steps:

• Check that current master version of heudiconv fails on GE data
• If it does fail, integrate modified version of heudiconv into BIDSifier, with some kind of switch based on input data