fixes to configuration auto-generating ported from auto-generate-config branch
_generate_all_config_items adjusted to return filename
modify astropy build to make the default configuration file
fixed unnecessarily long long in setup_helpers
implement code to install the default configuration file on import
updated documentation to reflect new behavior of on-import configuration setup
removed some debug code
added encode to subprocess communicate call to support py3.x
typo fix pointed out by @mdboom
Generation of configuration error message improvements
fixed encode/decode to making error mesages helpful in 2.x and 3.x
updated setup_helpers to run in build dir - this fixes py 3.x because before the 2to3ed version did not get run
Adjusted astropy/wcs/docstrings.py to work with configuration file builder on py 3.x
Moved ref_* scripts in coordinate accuracy tests to generate_ref_ast module.

This is necessary because the default configuration generation process visits all packages, including the test packages, so the import has to succeed even if pyast is not installed.
Make file cache work more efficiently in parallel from multiple processes or threads.
Partially addresses https://github.com/astropy/astroquery/pull/28
Don't display progress bars in child threads or processes
Add `download_files_in_parallel` convenience function.
Fix import of distribute in setup.py
Added a section on using setup.py develop.  This will provide a good segue into talking about virtualenv. Will also add the suggested docs for trying out a PR
Added a basic overview of using virtualenv