Update changelog in preparation for v0.2.3 release.
Merge branch 'master' of github.com:astropy/astropy
Merge pull request #1061 from astrofrog/fits/connect-fixes

Fixes to FITS Table connector
Merge pull request #1135 from astrofrog/config/pep8

PEP8 fixes in astropy/config
First attempt at refactoring Quantity into Numpy ndarray sub-class
Gets the tests at least passing with Quantity as an ndarray subclass.  This
required two changes in the existing behavior of the class (both of which could
be worked around, but for now these changes were the easiest way to get things
working):

1. Quantity.value always returns a Python type (such as `int` or `float`) for
   scalar quantities, even if the underlying object is a Numpy scalar array.

2. Quantity instances have a default unit of unscaled_dimensionless (previously
   it was erroneous to instantiate a Quantity without specifying a unit).
Fix behavior of ufuncs, added tests
Added tests for simple operations