Merge branch 'patch-3' into 'master'

Update cron.sh

See merge request ispconfig/ispconfig3!711

server/cron.sh

@@ -10,8 +10,9 @@ if [ -f /usr/local/ispconfig/server/lib/php.ini ]; then
 fi
 
 cd /usr/local/ispconfig/server
-/usr/bin/php -q \
+$(which php) -q \
     -d disable_classes= \
     -d disable_functions= \
     -d open_basedir= \
     /usr/local/ispconfig/server/cron.php
+    
\ No newline at end of file