BUG: Test and fix for subclasses of CacheableOffset (GH4609)
Merge branch 'offset_cache' of https://github.com/cancan101/pandas into cancan101-offset_cache

Conflicts:
	doc/source/release.rst
Merge pull request #4664 from jreback/hdf_series

ENH: In HDFStore, handle a passed Series in table format (GH4330)
BUG/API: (GH4584) to_hdf was raising when passing both arguments append and table
CLN: pep8 pandas/io/pytables
API: the ``fmt`` keyword now replaces the table keyword; allowed values are ``s|t``
     the same defaults as prior < 0.13.0 remain, e.g. ``put`` implies 's' (Storer) format
     and ``append`` imples 't' (Table) format