Added support for constructing a table from a list of dicts
split out doc rules to a separate page
moved astropy.sphinx.ext docs to docs section
Minor text fixes
adjust edit_on_github docstring to be in line with other extension docs
automodsumm doc tweaks
Added blurb at beginning of docguide
typo fix in edit_on_github
various title wording and ordering tweaks in developer docs
Reorganized building/releasing into three sections
Title change for leading dev section in docs
moved vision from toc to inline reference
Improves the output formatting of units.  The old method always used scientific notation, so you'd get string things like `u.min` displaying as `6 * 10^1 s` rather than just `60 s`.  The new method just builds on Python's "general purpose" float format `g`.
Add a test
Typo fixes pointed out by @mdboom
Fixes suggested/inspired by @iguananaut
Added support for column ordering, updated tests and docs
This should resolve the issue reported in #867 that when running
setup.py install (and in particular when installing Astropy with pip)
the ~/.astropy directory gets generated, when really it shouldn't be.
This commit does a few different things:

 * I've never been too thrilled about having code that can modify the
   system at import time. In the case of generating the default
   astropy.cfg and log I think we have a reasonable excuse, but let's
   try to keep stuff like that in astropy/__init__.py: For that reason I
   moved the logger module initialization code to an `_init_log()`
   function which is called in ``astropy.__init__``.  I also set up a
   default dummy-log so that stuff like ``from astropy import log`` will
   always work even if the real logger hasn't been initialized.

 * For the default config generation I got rid of the environment
   variable hack and just set ``_ASTROPY_SETUP_`` when running the
   subprocess.

   * This requires changing the imports that are only performed when
    ``not _ASTROPY_SETUP_`` to be at least attempted, and only raise an
    exception if we're not in setup mode (this way when the default
    config generator gets to those imports they will still work).

 * Ensured that no attempt is made to create a config file if
   ``_ASTROPY_SETUP_``.
This should fix the problems on Python 3. This forced me to finally go through much of astropy.io.fits and make it at least *importable* under Python 3, since the only places the wcs module was having issues was where it imports from io.fits.
A few more syntax fixes in io.fits for Python 3. These are easier to make in Astropy than in pyfits, which still supports Python 2.5