Fix compatibility with astropy0.4 coordinates API

The new [astropy coordinates api](http://docs.astropy.org/en/latest/coordinates/index.html) was merged yesterday.   We need to fix all the tests and add a compatibility layer for the change.

This will almost certainly have to push the 0.2 release back a week, but I'll put serious effort into it now/this weekend.  astroquery 0.2 should follow shortly behind astropy 0.4, ideally.