BUG: assignment with 0-dim arrays and a multi-index is buggy
This works in the non-multi-index case, so is a bug
http://stackoverflow.com/questions/23830248/potential-bug-pandas-multiindex-and-0-d-sized-values

```
np.random.seed(1234)
T = 100 # time
N = 80 # firms
TIndex = np.arange(0, T)
FIndex = np.arange(0, N)

index = pd.MultiIndex.from_product([TIndex, FIndex], names=['time', 'firm'])
df = pd.DataFrame(-999, columns=['A', 'w', 'l', 'a', 'x', 'X', 'd', 'profit'], index=index)
t, n = 0, 2
df.loc[(t,n), 'X'] = np.array(0)
```
