BUG: A zero length series written to HDF cannot be read back.
This happens with and empty series with numpy arrays for both the values and the index.

``` python
>>> import pandas as pd
>>> import numpy as np
>>> 
>>> with pd.get_store('foo.h5') as store:
...     s = pd.Series(np.array([], dtype=np.int64), index=np.array([], dtype=np.int64))
...     store['s'] = s
...     s = store['s']
... 
Traceback (most recent call last):
  File "<stdin>", line 4, in <module>
  File "/users/is/pross/workspace/pandas/git/pandas/pandas/io/pytables.py", line 349, in __getitem__
    return self.get(key)
  File "/users/is/pross/workspace/pandas/git/pandas/pandas/io/pytables.py", line 507, in get
    return self._read_group(group)
  File "/users/is/pross/workspace/pandas/git/pandas/pandas/io/pytables.py", line 1093, in _read_group
    return s.read(**kwargs)
  File "/users/is/pross/workspace/pandas/git/pandas/pandas/io/pytables.py", line 2247, in read
    return Series(values, index=index, name=self.name)
  File "/users/is/pross/workspace/pandas/git/pandas/pandas/core/series.py", line 657, in __init__
    data = SingleBlockManager(data, index, fastpath=True)
  File "/users/is/pross/workspace/pandas/git/pandas/pandas/core/internals.py", line 2942, in __init__
    block = make_block(block, axis, axis, ndim=1, fastpath=True)
  File "/users/is/pross/workspace/pandas/git/pandas/pandas/core/internals.py", line 1535, in make_block
    return klass(values, items, ref_items, ndim=ndim, fastpath=fastpath, placement=placement)
  File "/users/is/pross/workspace/pandas/git/pandas/pandas/core/internals.py", line 62, in __init__
    % (len(items), len(values)))
ValueError: Wrong number of items passed 1, indices imply 0
```

I have fixed this locally and will put in a PR.
