it seems you already have MariaDB installed, and it prevents installing MySQL. MariaDB is a drop-in replacement for MySQL and as such it should work with Django as is (excluding some minor issues).
You should be able to control the service using:
/etc/init.d/mysql start
/etc/init.d/mysql status
/etc/init.d/mysql stop
Here is more info regarding installation of MariaDB on CentOS