Use mysqlconnector as the sqlalchemy driver
Use mysqlconnector as the sqlalchemy driver

This allows us to avoid the deadlocking issue seen with MySQLdb:

https://blueprints.launchpad.net/neutron/+spec/switch-to-mysql-connector

Change-Id: I2b80aaa74e78f80cdba7c5ad3c06984ddabba443

yamt/networking-midonet,yamt/networking-midonet