Merge pull request #2541 from mdboom/misc/dont-import-ipython

Don't import IPython
Merge pull request #2522 from taldcroft/ascii-all-close

implements assert_almost_equals in ascii
Updated to latest version of astropy-helpers.

This version includes remaining changes that were made to the core package but not ported over to astropy-helpers.
Merge pull request #2547 from astrofrog/update-astropy-helpers

Updated to latest version of astropy-helpers.
Allow NDData and uncertainty to be set with Quantity
Merge pull request #2546 from mdboom/setup/ah_bootstrap-manifest

Add ah_bootstrap.py to MANIFEST.in
Merge pull request #2523 from dpshelio/fits_doc

Fix some minor formatting issues in the fits documentation.
Fixes for @nhmc comments, more pep8ification.
Merge pull request #2515 from embray/docs/old-whatsnew

Replace "What's New" page for previous versions with links
Tweak to remove unnecessary ' in coordinates index
Added missing "the"
Include astropy-helpers in the tarball.
Use lazyproperty
Fix doctest precision related failures
Force RA units to be degrees for allclose compare
Validate distance using Distance class
Last precision fix?
Merge pull request #2534 from taldcroft/coordinates-shortcut-transforms

Include UnitSphericalTransform in represent_as shortcuts and fix precision issues
Update coordinates index.rst
Update coordinates transforming.rst