Add default values in fits2bitmap help strings
Add default values in fits2bitmap help strings

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