Merge pull request #657 from nhmc/css_tweak

Add a maximum width to the main text body in the docs
Added a section to the What's new for v0.2 about the I/O framework
removed the fft_type option from convolve as per issue #660.  User can
specify their own fft; there's no need for astropy to test it.
refactor != -> np.isnan, len(shape) -> ndim
cleaned up tests
removed residual scipy junk (had considered testing scipy... no need)
convolve_dtype option added (no reason to force users into 128)
added warning about ignoring edge zeros etc. when kernel not normalized
Merge pull request #606 from taldcroft/use-system-sofa

setup.py: `--use-system-sofa` missing
fixed lost lines.  I don't know what happened still, but I think it has
something to do with checking out branches, loading branches into the
local vim buffer, then switching branches again without reloading
tiny fixes
restore numpy's default complex dtype
restored a lost comment
warnings -> log
added discussion of when to use your own fft and an example
only warn if options set
Added "What's new" section for the addition of the coordinates subpackage
fixed ref to astropy.coordinates
homogenized "what's new" indentation (2 spaces)
added open_api_page function
Added option to get URL without opening in browser (and cleaned up docstring)
Fixed find_api_page so that modules will also be located correctly