Move the [edit this page on github] link to the footer.
Merge pull request #691 from astrofrog/io/minor-hdf5-io-fixes

Improved opening/closing of files in HDF5 tests
Fixes #694: On Python 3.1, Fraction.from_float() must be used to instantiate a fraction from a float.
Update CSS to make right part of footer wider (and accomodate [edit this page on github] link)
Merge pull request #617 from mdboom/docs/edit-on-github-move-link

Adjust docs so "[edit this page on github]" appears next to "Page Source"
Merge pull request #694 from mdboom/unit/fraction_py31_bug

MacOS 10.8 test failures with Python 3.1
Update CHANGES.rst

Removed stuff from the changelog that wasn't meant to be there; moved stuff that was in the wrong release.
Refactored data I/O so that it is no longer attached to the Table class. This will allow it to be used for the NDData class as well as any other classes in future.
Make NDData inherit from DataIO to allow I/O handlers to be registered.
Check that data_class is a sub-class of DataIO
Moved the I/O registry docs outside of the Table docs.
Remove DataIO base class, simply assign the read/write methods manually to the Table and NDData classes.
Added 'read' and 'write' to __all__ for I/O registry
Added note for users about registry
Added documentation page for I/O registry to front page.
Added back @mdboom's fix to sort formats in exception
Whitespace
Updated CHANGES.rst, docs, and What's new, for refactored I/O framework.