np.delete fails when it could succeed
Calling `np.delete` on a `pandas.DataFrame` fails like so:

``` python
>>> df = pandas.DataFrame([[1,2,3],[4,5,6],[7,8,9]])

>>> np.delete(df, [1], axis=1)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Library/Python/2.7/site-packages/numpy-1.6.2-py2.7-macosx-10.8-intel.egg/numpy/lib/function_base.py", line 3390, in delete
    return wrap(new)
  File "/Library/Python/2.7/site-packages/pandas-0.9.0.dev_1e1c922-py2.7-macosx-10.8-intel.egg/pandas/core/frame.py", line 1506, in __array_wrap__
    columns=self.columns, copy=False)
  File "/Library/Python/2.7/site-packages/pandas-0.9.0.dev_1e1c922-py2.7-macosx-10.8-intel.egg/pandas/core/frame.py", line 392, in __init__
    copy=copy)
  File "/Library/Python/2.7/site-packages/pandas-0.9.0.dev_1e1c922-py2.7-macosx-10.8-intel.egg/pandas/core/frame.py", line 504, in _init_ndarray
    block = make_block(values.T, columns, columns)
  File "/Library/Python/2.7/site-packages/pandas-0.9.0.dev_1e1c922-py2.7-macosx-10.8-intel.egg/pandas/core/internals.py", line 461, in make_block
    do_integrity_check=do_integrity_check)
  File "/Library/Python/2.7/site-packages/pandas-0.9.0.dev_1e1c922-py2.7-macosx-10.8-intel.egg/pandas/core/internals.py", line 26, in __init__
    assert(len(items) == len(values))
AssertionError
```

But it could do this instead:

``` python
>>> np.delete(np.array(df), [1], axis=1)
array([[1, 3],
       [4, 6],
       [7, 9]])
```
