Astropy 0.4.1 on pypi is broken for python 2.6 due to missing _odict_py2 _fractions_py2 directories

Hi, 

For some reason the _odict_py2 _fractions_py2 directories are missing from astropy/utils/compat
in the astropy-0.4.1 tar.gz on pypi.

```
$ ls astropy-0.4/astropy/utils/compat/ 
_argparse     _fractions_py2  _gzip_py2    numpycompat.py  subprocess.py
argparse.py   futures         __init__.py  odict.py        _subprocess_py2
fractions.py  gzip.py         misc.py      _odict_py2
$ ls astropy-0.4.1/astropy/utils/compat/
_argparse     futures    __init__.py   misc.pyc        odict.pyc
argparse.py   gzip.py    __init__.pyc  numpycompat.py  subprocess.py
fractions.py  _gzip_py3  misc.py       odict.py
```

This leads to either breakage during the installation or breakage during running astropy on python 2.6.
For example: 

```
(pyenv26)[koposov@calx115 astropy-0.4.1 19:56:14]$ python setup.py build
git submodule command failed unexpectedly:
fatal: Not a git repository (or any of the parent directories): .git

Traceback (most recent call last):
  File "setup.py", line 18, in <module>
    import astropy
  File "/tmp/test26/astropy-0.4.1/astropy/__init__.py", line 77, in <module>
    from . import config as _config
  File "/tmp/test26/astropy-0.4.1/astropy/config/__init__.py", line 12, in
<module>
    from .configuration import *
  File "/tmp/test26/astropy-0.4.1/astropy/config/configuration.py", line 27,
in <module>
    from ..utils.exceptions import AstropyWarning, AstropyDeprecationWarning
  File "/tmp/test26/astropy-0.4.1/astropy/utils/__init__.py", line 15, in
<module>          
    from .compat.odict import OrderedDict                                   
  File "/tmp/test26/astropy-0.4.1/astropy/utils/compat/odict.py", line 7, in
<module>                                                                    
    from ._odict_py2 import *
ImportError: No module named _odict_py2
``` 

Cheers,
        Sergey