Some slight tweaks to CompositeModels for the v0.3.2 release.  This doesn't add much improvement or fix any issues--instead it addresses issues like #1836 by being clearer about what these classes don't currently support.  It also slightly improves their text representations.
Remove some deprecated things in `units` and `wcs`.
Merge pull request #2115 from pllim/vo-cat-io

Expand functionalities for VO catalog and database classes
Don't generate the config file any longer, just keep it in the repo and
copy it over.
Add a test.
Remove save functionality from config
First pass at moving around all of the configuration options.  Tests passing.
Don't warn on import
Notate the version at which configuration items were renamed.
Fix more warnings on import.
Minor docstring improvements.
Make configuration items show up in docs
Update config doc pages.
Document configuration changes.
Reorganize astropy.cfg based on general categories in docs.
Correct APE5 -> APE3
Test ScienceStateAlias.
Some Sphinx doc fixes.
Fix for Python 2.6 and 3.1.
Remove obsolete comment