fixing tests, so they take into account availability of optional dependencies
Code uses OrderedDict (new in python 2.7), so I suggest to remove python 2.6 support (and do that in this PR) Adding it back with the dependency of ordereddict for those builds.
DO not merge yet.
Including:
astropy-helpersto 1.0.5ci-helperswith travisCode uses) Adding it back with the dependency ofOrderedDict(new in python 2.7), so I suggest to remove python 2.6 support (and do that in this PRordereddictfor those builds.