update label color when disabled_color changes
update label color when disabled_color changes

bionoid/kivy,janssen/kivy,matham/kivy,jkankiewicz/kivy,rnixx/kivy,cbenhagen/kivy,aron-bordin/kivy,kivy/kivy,rnixx/kivy,Cheaterman/kivy,KeyWeeUsr/kivy,manthansharma/kivy,kivy/kivy,kivy/kivy,rnixx/kivy,CuriousLearner/kivy,janssen/kivy,manthansharma/kivy,matham/kivy,janssen/kivy,jegger/kivy,jkankiewicz/kivy,akshayaurora/kivy,darkopevec/kivy,rafalo1333/kivy,Cheaterman/kivy,arlowhite/kivy,LogicalDash/kivy,KeyWeeUsr/kivy,Cheaterman/kivy,janssen/kivy,andnovar/kivy,manthansharma/kivy,darkopevec/kivy,akshayaurora/kivy,arlowhite/kivy,aron-bordin/kivy,bionoid/kivy,tony/kivy,el-ethan/kivy,tony/kivy,bionoid/kivy,kived/kivy,autosportlabs/kivy,rafalo1333/kivy,jkankiewicz/kivy,inclement/kivy,matham/kivy,jegger/kivy,LogicalDash/kivy,el-ethan/kivy,LogicalDash/kivy,manthansharma/kivy,el-ethan/kivy,inclement/kivy,autosportlabs/kivy,kived/kivy,cbenhagen/kivy,tony/kivy,aron-bordin/kivy,inclement/kivy,jegger/kivy,jegger/kivy,andnovar/kivy,rafalo1333/kivy,akshayaurora/kivy,bionoid/kivy,autosportlabs/kivy,LogicalDash/kivy,cbenhagen/kivy,kived/kivy,matham/kivy,darkopevec/kivy,Cheaterman/kivy,darkopevec/kivy,KeyWeeUsr/kivy,arlowhite/kivy,jkankiewicz/kivy,CuriousLearner/kivy,aron-bordin/kivy,KeyWeeUsr/kivy,CuriousLearner/kivy,andnovar/kivy