added test_imports to make sure all packages successfully import
added test_imports to make sure all packages successfully import

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