HDFStore('file.ext') can't load HDF5 stores created by pytables
Hello,

A store created outside of pandas can't be loaded into pandas with the HFDStore() method.

An error occurs : AttributeError: Attribute 'pandas_type' does not exist in node: '/'

To reproduce, create a store using pytables, and try to load it in pandas. It will raise this error.

In my opinion, if pandas is supposed to suppord HDF5, it should do so, without only supporting stores created in pandas. If nothing can be done, can you tell me what is is attribute so that I can create it when I create my store with pytables ? 

Thanks !
