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. 
That explains it.  Thanks!

On Wed, Oct 8, 2014 at 4:48 PM, Brittain Hard <notifications@github.com>
wrote:

> In blaze/compute/numpy.py:
>
> > @@ -64,12 +64,6 @@ def compute_up(t, x, **kwargs):
> >      return -x
> >
> >
> > -@dispatch(Selection, np.ndarray)
> > -def compute_up(t, x, **kwargs):
> > -    predicate = compute(t.predicate, {t.child: x})
> > -    return x[predicate]
>
> There was a duplicate function:
>
> @dispatch(Selection, np.ndarray)
> def compute_up(sel, x, **kwargs):
>     return x[compute(sel.predicate, {sel.child: x})]
>
> This one was better than that one, at least in my opinion.
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/ContinuumIO/blaze/pull/720/files#r18620172>.
>