DataFrame.from_records do not support record have sub array?
The code is like below, which i thought it should work, but it doesn't, it raise an exception saying `Data must be 1-dimensional`. Is this by design or an defect? if by design how should i walk around this? pandas version is 0.15.1

``` py
dt_type = np.dtype([
    ('k', 'i4'),
    ('v', 'i4', 2)
])

dt = np.array([(123457803, (1, 2))], dtype=dt_type)
print(dt)
df = pd.DataFrame.from_records(dt)
print(df)
```

``` exception
  File "/home/aulphar/Documents/dev/proj/FIS/tools/data_exportor.py", line 90, in main
    df = pd.DataFrame.from_records(dt)
  File "/usr/local/lib/python3.4/dist-packages/pandas/core/frame.py", line 877, in from_records
    columns)
  File "/usr/local/lib/python3.4/dist-packages/pandas/core/frame.py", line 4684, in _arrays_to_mgr
    arrays = _homogenize(arrays, index, dtype)
  File "/usr/local/lib/python3.4/dist-packages/pandas/core/frame.py", line 4998, in _homogenize
    raise_cast_failure=False)
  File "/usr/local/lib/python3.4/dist-packages/pandas/core/series.py", line 2684, in _sanitize_array
    raise Exception('Data must be 1-dimensional')
Exception: Data must be 1-dimensional
```
