Adding missing .exists method to the mixed storage
Adding missing .exists method to the mixed storage

aaxx/thumbor,Jimdo/thumbor,food52/thumbor,dhardy92/thumbor,dhardy92/thumbor,scorphus/thumbor,grevutiu-gabriel/thumbor,food52/thumbor,thumbor/thumbor,jiangzhonghui/thumbor,davduran/thumbor,kkopachev/thumbor,thumbor/thumbor,raphaelfruneaux/thumbor,aaxx/thumbor,lfalcao/thumbor,food52/thumbor,2947721120/thumbor,fanhero/thumbor,jdunaravich/thumbor,raphaelfruneaux/thumbor,dhardy92/thumbor,lfalcao/thumbor,figarocms/thumbor,wking/thumbor,2947721120/thumbor,abaldwin1/thumbor,BetterCollective/thumbor,fanhero/thumbor,fanhero/thumbor,Jimdo/thumbor,gselva/thumbor,adeboisanger/thumbor,wking/thumbor,felipemorais/thumbor,voxmedia/thumbor,thumbor/thumbor,jdunaravich/thumbor,kkopachev/thumbor,MaTriXy/thumbor,camargoanderso/thumbor,jiangzhonghui/thumbor,adeboisanger/thumbor,suwaji/thumbor,grevutiu-gabriel/thumbor,scorphus/thumbor,jiangzhonghui/thumbor,fanhero/thumbor,jdunaravich/thumbor,raphaelfruneaux/thumbor,MaTriXy/thumbor,BetterCollective/thumbor,Bladrak/thumbor,davduran/thumbor,gi11es/thumbor,2947721120/thumbor,gi11es/thumbor,felipemorais/thumbor,aaxx/thumbor,suwaji/thumbor,felipemorais/thumbor,gselva/thumbor,jdunaravich/thumbor,grevutiu-gabriel/thumbor,Jimdo/thumbor,abaldwin1/thumbor,scorphus/thumbor,okor/thumbor,wking/thumbor,food52/thumbor,abaldwin1/thumbor,suwaji/thumbor,BetterCollective/thumbor,felipemorais/thumbor,marcelometal/thumbor,lfalcao/thumbor,figarocms/thumbor,voxmedia/thumbor,figarocms/thumbor,kkopachev/thumbor,marcelometal/thumbor,abaldwin1/thumbor,lfalcao/thumbor,MaTriXy/thumbor,adeboisanger/thumbor,Jimdo/thumbor,kkopachev/thumbor,adeboisanger/thumbor,gi11es/thumbor,raphaelfruneaux/thumbor,marcelometal/thumbor,camargoanderso/thumbor,suwaji/thumbor,gselva/thumbor,gselva/thumbor,scorphus/thumbor,figarocms/thumbor,camargoanderso/thumbor,wking/thumbor,Bladrak/thumbor,thumbor/thumbor,okor/thumbor,aaxx/thumbor,davduran/thumbor,2947721120/thumbor,davduran/thumbor,voxmedia/thumbor,camargoanderso/thumbor,grevutiu-gabriel/thumbor,okor/thumbor,jiangzhonghui/thumbor,MaTriXy/thumbor