Add docker-based integration test infrastructure

[heynickc]

To be consistent with SqlServer, Postgres, Cassandra plugins, test against a container running MySql

[alexvaluyskiy]

@heynickc Not necessary. We have AppVeyor CI and it worked for integration tests before. I have to realize why it stopped working

[heynickc]

@alexvaluyskiy this is an additional feature, not a bug fix. this is how we test our other plugins against live databases to allow integration testing against different versions of the databases

[heynickc]

@alexvaluyskiy if you would like to discontinue testing our persistence plugins this way, please bring it up with the core team to reach a consensus and we will discontinue testing this way across all plugins

[Aaronontheweb]

@alexvaluyskiy better off standardizing on Docker

[heynickc]

disregard, since this is a contrib package now