Merge pull request #5328 from jreback/hdf_repr

BUG: repr/str of storers in HDFStore was calling an incorrect method
Merge pull request #5325 from jreback/df_display

BUG: bug when trying to display an embedded PandasObject (GH5324)
TST/BUG: allow invalid Timestamps to pass thru as datetimes when operating with offsets
         related (GH5312)