[BUG Prune docker images in cron-tmux (#27)

Author: ADGEfficiency

Makefile

@@ -82,7 +82,5 @@ docker-setup:
 
 docker-push:
 	sudo heroku auth:token | sudo docker login --username=_ registry.heroku.com --password-stdin
-	mkdir -p clear-docker-cache
-	touch "clear-docker-cache/$(shell date)"
 	sudo heroku container:push web -a climate-news-db --recursive
 	sudo heroku container:release web -a climate-news-db

cron-tmux.sh

@@ -2,4 +2,5 @@
 . /home/ubuntu/.profile
 . /home/ubuntu/.bashrc
 cd /home/ubuntu/climate-news-db && /usr/bin/tmux new -d -s cron-scraper
-/usr/bin/tmux send-keys -t cron-scraper "/usr/bin/make scrape; sudo shutdown" C-m
+docker system prune --all --force
+/usr/bin/tmux send-keys -t cron-scraper "/usr/bin/make scrape >> ~/cron-log.txt && sudo shutdown" C-m