add test to make sure .units works, and issues a DeprecationWarning
add test to make sure .units works, and issues a DeprecationWarning

tbabej/astropy,pllim/astropy,bsipocz/astropy,joergdietrich/astropy,stargaser/astropy,saimn/astropy,MSeifert04/astropy,mhvk/astropy,astropy/astropy,kelle/astropy,stargaser/astropy,aleksandr-bakanov/astropy,aleksandr-bakanov/astropy,lpsinger/astropy,joergdietrich/astropy,dhomeier/astropy,bsipocz/astropy,pllim/astropy,astropy/astropy,DougBurke/astropy,dhomeier/astropy,AustereCuriosity/astropy,saimn/astropy,larrybradley/astropy,joergdietrich/astropy,stargaser/astropy,lpsinger/astropy,larrybradley/astropy,kelle/astropy,lpsinger/astropy,tbabej/astropy,lpsinger/astropy,aleksandr-bakanov/astropy,tbabej/astropy,StuartLittlefair/astropy,joergdietrich/astropy,joergdietrich/astropy,AustereCuriosity/astropy,AustereCuriosity/astropy,pllim/astropy,astropy/astropy,mhvk/astropy,StuartLittlefair/astropy,larrybradley/astropy,dhomeier/astropy,larrybradley/astropy,funbaker/astropy,pllim/astropy,DougBurke/astropy,saimn/astropy,astropy/astropy,larrybradley/astropy,mhvk/astropy,kelle/astropy,funbaker/astropy,DougBurke/astropy,stargaser/astropy,kelle/astropy,MSeifert04/astropy,MSeifert04/astropy,AustereCuriosity/astropy,lpsinger/astropy,bsipocz/astropy,aleksandr-bakanov/astropy,bsipocz/astropy,tbabej/astropy,funbaker/astropy,dhomeier/astropy,mhvk/astropy,mhvk/astropy,kelle/astropy,StuartLittlefair/astropy,StuartLittlefair/astropy,funbaker/astropy,pllim/astropy,tbabej/astropy,AustereCuriosity/astropy,saimn/astropy,astropy/astropy,MSeifert04/astropy,dhomeier/astropy,saimn/astropy,DougBurke/astropy,StuartLittlefair/astropy