Make TransformGraph._cached_classes into public frame_set

@taldcroft's suggestion
add test for transforming SkyCoord with None frame
equal->allclose for conesearch test
Fix copying-related failures (had been xfailed)
Remove Jenkins Build Status from README

shining panda no longer exists
Fix test_frames and APE5 api tests  for py 3 failures  due to rounding
add __bool__ in addition to __nonzero__ for py 3.x compat
Fix for failing py 3.x behavior due to getitem/getattr interaction
Merge pull request #2474 from eteq/remove-shiningpanda-readme

Remove Jenkins Build Status from README
Include Numpy include path when building wcs test extension.
Fixing documentation links, warnings, PEP8 in stat, config, constants
Make work when astropy isn't installed.
Fix NDData issues with units and uncertainties

Includes tests, and closes #2393
Ensure that members of NDData are new copies instead of references

In both _arithmetic and convert_unit_to the result ought to be independent of the input and it wasn't.
Closes #2394
Add workaround for creating bool array in numpy 1.5.1
Fix initialization of NDData by NDData

Closes #2406
Set flags of the result in convert_unit_to

Closes #2409
Ensure that the wcs attribute of the result of _arithmetic is a copy, not reference

Closes #2410
Fix slicing of a single element in an NDData with mask or flags

Closes #2170
Convert NDData to numpy masked array if mask is set

Closes #2414