Fixed breakages introduced by astropy-2.0
This PR fixes two problems introduced by the release of astropy v2
- crappy test of
TimeSeriesList.coalesce
was exposed, needed fixes - astropy 2 starts using numpy 1.13's new
__array_ufunc__
API, so we need to replicate that to get theTimeSeries
->StateTimeSeries
conversion to work for numpy ufunc comparisons