test failing on Windows

After installing from source, I'm running nosetests. 

Everything runs, except for one unit test.

```
  File "C:\Users\FL232714\Documents\GitHub\tofu\tofu\tests\tests09_tutorials\tests01_runall.py", line 20, in <module>
    _TFROOT = _HERE[:-_HERE[::-1].index('/tofu'[::-1])-len('/tofu')]
ValueError: substring not found
```

Will try to fix.