Provide ability to specify JDBC connection string #354

For example our MySQL server on Azure requires the following:
jdbc:mysql://...?useSSL=true&requireSSL=true&useTimezone=true&serverTimezone=UTC&enabledTLSProtocols=TLSv1.2

• There's no way to specify those parameters with your connector (and so I get "No appropriate protocol"), after fixing that I'd probably get error about wrong timestamp params.
• Specifying the things with one parameter makes Spring Boot / Docker / Kubernetes production deployments easier (just 1 param, not 10)