Document tested JDBC drivers and versions

[jordansissel]

Issue #186 reminded me that we don't document what drivers and driver versions we test with. Especially considering this plugin is on the support matrix, we really need to be clear about what drivers (and driver versions) we expect to work or have at least anecdotal reports of success.

[jordansissel]

I looked at the specs in this repo and it looks like only Derby, and no other database backend, is used for testing.

[PhaedrusTheGreek]

Additionally, if the driver mode is called out specifically, like "jdbc:jtds:sybase://..", and we don't support it, then should we log an error at least?