add clean_images.sh, fixes #4

clean_images.sh

@@ -0,0 +1,24 @@
+#!/bin/bash
+
+# deletes old images on heroku
+# heroku provides only 300 MB available disk space
+
+# number of files to delete (2 files ~ 400B)
+amount="50000" # about 20MB
+
+# max free MB (on /) to trigger deletion
+trigger="50"
+
+available=`df -m / | awk 'NR==2 { print $4 }'` # MB available on /
+if [ "$available" -le "$trigger" ]; then
+  echo "Deleting old images"
+  for file in `ls -1tr "/app/skins/faces" | head -n $amount`; do
+    rm -rf "/app/skins/faces/$file"
+  done
+  for file in `ls -1tr "/app/skins/helms" | head -n $amount`; do
+    rm -rf "/app/skins/helms/$file"
+  done
+  echo "done."
+else
+  echo "More than $trigger MB are available ($available MB), not deleting!"
+fi