Use select_column if possible when read_hdf
If in `pd.read_hdf(..., columns=['col_name], ...)` we have only one column, then it would be much faster to use `store.select_column()` instead of `store.column()`.

https://github.com/pandas-dev/pandas/blob/fa231e8766e02610ae5a45e4b2bc90b6c7e9ee6f/pandas/io/pytables.py#L368

Any caveats on implementing this?