Test compute numpy

This is almost ready for merging. I have one problem though, with the function on line 49:

```
@dispatch(BinOp, base, np.ndarray)
def compute_up(t, lhs, rhs, **kwargs):
    return t.op(lhs, rhs)
```

Had a lot of trouble figuring out how to call this function, figuring out what it wanted for inputs. Any feedback on this would be appreciated. 
To me these test seem simple and clear.  That is probably just my own aesthetics though.