pandas needs a package-wide config object?
I'm working on the next Unicode PR, which incorporates some global configurables,
and I can't seem to find a convention for handling that uniformly in pandas.

format.py has `_GlobalPrintConfig`/`print_config`, and core.api has the corresponding
`set_printoptions`, It looks to me like they need to be integrated into something more general.

Examples from other projects:
- `matplotlib` has rcParams
- `IPython` does things differently with  [config.configurable](http://ipython.org/ipython-doc/stable/api/generated/IPython.config.configurable.html) , but still has a well defined way of 
  using/adding configurables.

I suggest a new `core.config` module to hold all configurables, 
It will take over print_config (set_printoptions will keep working),
but  will provide a more general namespacing scheme for configurables along with a 
getter/setter to be added to core.api.

Once the getter/setter convention is put into place and used uniformly in the code, 
the underlying implementation can change as necessary when pandas grows.

if this  sounds reasonable, I can follow up with a PR. @wesm?
