[yt-dev] Issue #768: Units and exponents (yt_analysis/yt)

[Matthew Turk]

New issue 768: Units and exponents
https://bitbucket.org/yt_analysis/yt/issue/768/units-and-exponents

Matthew Turk:

Exponents don't seem to change the units of a YTArray.

```
#!python
from yt.units import cm
import numpy as np

cm_arr = np.array([1.0,1.0]) * cm

print cm**3
print cm_arr * cm_arr
print cm_arr**3
```

Responsible: ngoldbaum