ENH: add pandas.hdfstore suppport


includes some other commits to make testing clean
- https://github.com/jreback/into/commit/82a6546ee5c6465a851601873f00ff05109a3c0c is in another PR already
- https://github.com/jreback/into/commit/836d5caaf2e3189882a53df343a18a785672c3a2 should be cherry-picked

- Added into support to include chunking / column selection / reading and writing

the use of uri's in resource that need a hierarchical disambiguation
based on priority and the raising of ``NotImplementedError`` by matches
that do not wish to be a resource for that particular uri

IOW. a higher-priority uri matches (e.g. .h5), but the data is
actually PyTables, so HDFStore 'passes' on the processing. PyTables
is next in the chain so it will then process.

Note that a uri can be more fully-disambiguated via a head element
The default is ``hdfstore`` (this only matters for writing), reading
is unambiguous.

e.g.

```
....../file.h5 -> hdfstore
hdfstore://....../file.hdf5|h5 -> hdfstore
pytables://....../file.hdf5|h5 -> pytables
h5py://........../file.hdf5|h5 -> h5py
```
Ah my apologies, I didn't understand these.    What would this fixture look like as a context manager?  How would it be uglier?  

Perhaps my hesitance here is just due to not understanding the more advanced features of pytest.  I'll read a bit more in the next few days.

Incidentally, why don't you use pytest in pandas?