Fix _CompoundModelMeta.__dir__ for Python < 3.3.  Annoyingly, object.__dir__ nor type.__dir__ were defined before then.
Fix _CompoundModelMeta.__dir__ for Python < 3.3.  Annoyingly, object.__dir__ nor type.__dir__ were defined before then.

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