monkeypatch units to have "degree" and "degrees" and "hour" and "hours"
(no radians; not used) and test for it
travis tests updated to include astropy stable tests
attempt to fix monkeypatching; it doesn't work
slight advancement but still no success in monkeypatching
major refactor: allow compatibility with astropy 0.2.4
Merge pull request #208 from keflavich/monkeypatch_plural_units

Monkeypatch to allow compatibility with astropy < 0.3.dev4957