DataFrame constructor (dict of tuples)
This might be an API change instead of an issue, but just in case, could you please confirm that this should crash?  

```
  DataFrame({'a':(1,2,3)})                
```

with this error: 

```
 *** ValueError: If use all scalar values, must pass index
```

Using a dictionary where the values are equal length tuples used to work in 0.7. 

Thanks!
