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
rewording according to discussion on github
Initial cut at Using SkyCoord docs
Allow SkyCoord input as a numpy array
Mostly finished skycoord initialization docs
Add reference to angle creation section
Allow SkyCoord input as a numpy array
Finish up SkyCoord related updates
PEP8 fixes