Switch to the dummy backend on docker dev
Switch to the dummy backend on docker dev

This makes emails not fail, which was causing
send_video_comment_notification to also fail.

wevoice/wesub,ujdhesa/unisubs,eloquence/unisubs,wevoice/wesub,pculture/unisubs,ofer43211/unisubs,wevoice/wesub,ofer43211/unisubs,pculture/unisubs,wevoice/wesub,eloquence/unisubs,ReachingOut/unisubs,eloquence/unisubs,ReachingOut/unisubs,ujdhesa/unisubs,pculture/unisubs,norayr/unisubs,ujdhesa/unisubs,ReachingOut/unisubs,ujdhesa/unisubs,norayr/unisubs,ofer43211/unisubs,ofer43211/unisubs,pculture/unisubs,norayr/unisubs,eloquence/unisubs,norayr/unisubs,ReachingOut/unisubs