title: Using pandas and PyTables (3.1.1) at the same time, re-opening an already open file
body: <p>I use pandas and pytables (3.1.1) at once. The problem is that I already opened an HDF5 file with pytables and when I try to create a new HDF5Store with pandas</p>
  
  <pre><code>hdf5store = HDFStore(...)
  </code></pre>
  
  <p>I get the following error:</p>
  
  <pre><code>  File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/pandas/io/pytables.py", line 281, in __init__
      self.open(mode=mode, warn=False)
    File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/pandas/io/pytables.py", line 387, in open
      self._handle = h5_open(self._path, self._mode)
    File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/pandas/io/pytables.py", line 154, in h5_open
      return tables.openFile(path, mode)
    File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/tables/_past.py", line 35, in oldfunc
      return obj(*args, **kwargs)
    File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/tables/file.py", line 296, in open_file
      _FILE_OPEN_POLICY))
  ValueError: The file '/tmp/temp_folder_for_pypet_tests/experiments/tests/HDF5/merge1.hdf5' is already opened.  Please close it before reopening.  HDF5 v.1.8.4-patch1, FILE_OPEN_POLICY = 'strict'
  </code></pre>
  
  <p>How can I tell pandas to not reopen the file but simply use the already given file handle?</p>
  
  <p>Thanks a lot!</p>