added Msun alias for solar mass unit
added Msun alias for solar mass unit

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