More fixes to make Oasis work with FEniCS 2018.1.0

[benzwick]

Most of the example problems now run with FEniCS 2018.1.0.

The following problems still have some issues that I was unable to fix:

• NSCoupled/Nozzle2D.py
• NSCoupled/SkewedFlow.py
• NSfracStep/FlowPastSphere3D.py
• NSfracStep/SkewedFlow.py

[mikaem]

Thanks a lot @benzwick for this update. Seems to me that it's all minor changes so I'll just go ahead and merge it.