Merge branch '3.2-stable' into astropy

Conflicts:
	.coveragerc
	.travis.yml
	MANIFEST.in
	docs/io/fits/users_guide/users_headers.rst
	docs/source/appendix/header_transition.rst
	docs/source/conf.py
	docs/source/developers_guide/developers_guide.rst
	setup.cfg

Conflicts:

	astropy/io/fits/card.py
	astropy/io/fits/column.py
	astropy/io/fits/convenience.py
	astropy/io/fits/core.py
	astropy/io/fits/file.py
	astropy/io/fits/fitsrec.py
	astropy/io/fits/hdu/base.py
	astropy/io/fits/hdu/compressed.py
	astropy/io/fits/hdu/image.py
	astropy/io/fits/hdu/table.py
	astropy/io/fits/header.py
	astropy/io/fits/scripts/fitscheck.py
	astropy/io/fits/tests/test_checksum.py
	astropy/io/fits/tests/test_core.py
	astropy/io/fits/tests/test_diff.py
	astropy/io/fits/tests/test_header.py
	astropy/io/fits/util.py
	docs/io/fits/usage/headers.rst
	docs/io/fits/usage/image.rst
	docs/io/fits/usage/table.rst
	docs/io/fits/usage/unfamiliar.rst
	docs/io/fits/usage/verification.rst
	docs/io/fits/users_guide/users_intro.rst
	docs/io/fits/users_guide/users_tutorial.rst
Update deprecated decorators in astropy.io.fits to refer to the corresponding *astropy* version in which those interfaces are deprecated (some of them have been ever since 0.1) rather than the PyFITS version, which was no doubt confusing...
An odd bug that's occurring with Numpy 1.9 on Python 3.4 only (?).  I can't even reproduce this in PyFITS at all, and it occurs randomly in Astropy.  It appears that np.char.replace can actually resize the original array because it trims any null bytes it encounters in each string.  So for example an S5 array with a buffer like 'abc\x00\x00defg\x00' is converted to an S4 array with a buffer like 'abc\x00defg' followed by gibberish.  I don't fully understand why this sometimes leads to problems, but the problems occur when trying to interpret the bytes in the array buffer as strings representing floats.  Just filling any nulls in the array buffer with spaces circumvents the problem.
Added a changelog entry; rather than duplicate all of the PyFITS changelog, just link to relevant PyFITS docs.
Noticed while reviewing the PR that this method was needlessly duplicated in the merge
Fix missing reference in documentation
Fix still more warnings in the docs build
Merge pull request #2056 from embray/pyfits-merge

PyFITS fixes for inclusion in Astropy 0.3.1