Fixed missing db.php insert and mysql service name

Installer was missing `sed -i "s|YOUR_ROOT_MYSQL_PASSWORD|$password|" /etc/zpanel/panel/cnf/db.php` and also mysql service was referenced as mysqld service.
Fixing cron task creation

`/var/spool/cron/crontabs: 0644 -> 0744` to allow "Cron Tasks" to be created.
Merge pull request #18 from stokes84/master

Fixed missing db.php insert and mysql service name