Small fixes

update-app.sh

@@ -1,14 +1,24 @@
 #!/bin/sh
+
+# fail script if one command fails
+set -e
+
+# we need at least one argument
 if [ $# -eq 0 ]
   then
 	echo "usage: ./update-app.sh \$app"
 	exit 0
 fi
-
 APP=$1
 
+# download app
 cd ~/wp-content/plugins
 wget https://downloads.wordpress.org/plugin/$APP.zip
+
+# install app
 rm -rf $APP
 unzip $APP.zip
 
+# clean up
+rm $APP.zip
+