Add a few more tests initializing using xyz_axis and unit.
Add a few more tests initializing using xyz_axis and unit.

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