change to getting frame attributes from dictionary on-creation of transforms
change to getting frame attributes from dictionary on-creation of transforms

This makes it so that the frame transform graph doesn't actually try to 
create frame attributes.

lpsinger/astropy,dhomeier/astropy,mhvk/astropy,aleksandr-bakanov/astropy,dhomeier/astropy,pllim/astropy,lpsinger/astropy,saimn/astropy,StuartLittlefair/astropy,dhomeier/astropy,larrybradley/astropy,bsipocz/astropy,mhvk/astropy,stargaser/astropy,dhomeier/astropy,pllim/astropy,StuartLittlefair/astropy,lpsinger/astropy,mhvk/astropy,bsipocz/astropy,saimn/astropy,MSeifert04/astropy,astropy/astropy,stargaser/astropy,aleksandr-bakanov/astropy,StuartLittlefair/astropy,dhomeier/astropy,aleksandr-bakanov/astropy,larrybradley/astropy,pllim/astropy,mhvk/astropy,astropy/astropy,saimn/astropy,StuartLittlefair/astropy,larrybradley/astropy,stargaser/astropy,astropy/astropy,MSeifert04/astropy,bsipocz/astropy,aleksandr-bakanov/astropy,mhvk/astropy,lpsinger/astropy,larrybradley/astropy,larrybradley/astropy,astropy/astropy,pllim/astropy,StuartLittlefair/astropy,astropy/astropy,stargaser/astropy,lpsinger/astropy,MSeifert04/astropy,bsipocz/astropy,pllim/astropy,saimn/astropy,saimn/astropy,MSeifert04/astropy