HDF5 files not compatible between python 2 and 3 ?
I have a problem loading a h5 file from python 3 to python 2 and vice versa. I can't post the code which generate h5 file because is part of a big project. I'll try to upload h5 file directly later.

Here is the error when I load **FROM python 3.3** an h5 file created **BY python 2.7**:

```
Traceback (most recent call last):
  File "/home/hadim/local/virtualenvs/st3/src/master/build/lib.linux-x86_64-3.3/pandas/core/index.py", line 1539, in _get_level_number
    level = self.names.index(level)
ValueError: 'side' is not in list

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "main.py", line 49, in <module>
    meta = SimuIO().read(results_file)
  File "../kt_simul/io/simuio.py", line 210, in read
    KD.spbL.traj = spbs.xs('A', level='side').values.T[0]
  File "/home/hadim/local/virtualenvs/st3/src/master/build/lib.linux-x86_64-3.3/pandas/core/frame.py", line 2335, in xs
    loc, new_ax = labels.get_loc_level(key, level=level)
  File "/home/hadim/local/virtualenvs/st3/src/master/build/lib.linux-x86_64-3.3/pandas/core/index.py", line 2322, in get_loc_level
    level = self._get_level_number(level)
  File "/home/hadim/local/virtualenvs/st3/src/master/build/lib.linux-x86_64-3.3/pandas/core/index.py", line 1542, in _get_level_number
    raise Exception('Level %s not found' % str(level))
Exception: Level side not found
Closing remaining open files: simu.h5... done 
```

Here is the error when I load **FROM python 2.7** an h5 file created **BY python 3.3**:

```
Traceback (most recent call last):
  File "main.py", line 49, in <module>
    meta = SimuIO().read(results_file)
  File "/home/hadim/.phd/dev/kt_simul/kt_simul/io/simuio.py", line 197, in read
    param_root = build_tree(store['params'])
  File "/home/hadim/local/virtualenvs/st/src/master/pandas/io/pytables.py", line 289, in __getitem__
    return self.get(key)
  File "/home/hadim/local/virtualenvs/st/src/master/pandas/io/pytables.py", line 422, in get
    return self._read_group(group)
  File "/home/hadim/local/virtualenvs/st/src/master/pandas/io/pytables.py", line 930, in _read_group
    return s.read(**kwargs)
  File "/home/hadim/local/virtualenvs/st/src/master/pandas/io/pytables.py", line 2194, in read
    values = self.read_array('block%d_values' % i)
  File "/home/hadim/local/virtualenvs/st/src/master/pandas/io/pytables.py", line 1776, in read_array
    data = node[:]
  File "/home/hadim/local/virtualenvs/st/local/lib/python2.7/site-packages/tables/vlarray.py", line 661, in __getitem__
    return self.read(start, stop, step)
  File "/home/hadim/local/virtualenvs/st/local/lib/python2.7/site-packages/tables/vlarray.py", line 801, in read
    outlistarr = [atom.fromarray(arr) for arr in listarr]
  File "/home/hadim/local/virtualenvs/st/local/lib/python2.7/site-packages/tables/atom.py", line 1151, in fromarray
    return cPickle.loads(array.tostring())
ValueError: unsupported pickle protocol: 3
Closing remaining open files: simu.h5... done
```

---

Version command run:

``` python
import sys
print(sys.version)
import numpy
print(numpy.__version__)
import tables
print(tables.__version__)
import pandas
print (pandas.__version__)
```

Python 3 shell:

```
3.3.1 (default, Apr 17 2013, 22:30:32) 
[GCC 4.7.3]
1.7.1
3.0.0
0.12.0.dev-404dfab
```

Python 2 shell:

```
2.7.4 (default, Apr  9 2013, 18:05:19) 
[GCC 4.7.3]
1.7.1
3.0.0
0.12.0.dev-4c2d050
```
