introduced: connection specific properties + property: instanceId

should be solution for #253.

Please note, this brings API breaking changes, namely:

* output log format has been extended with `|instanceId|` value
* P6LogQuery public API changed, P6OptionsRepository (class) -> OptionsRepository (interface)

So my suggestion would be to go for 2.2.0 version, once this goes upstream.

I guess, I'll introduce `migration.md` to sumarize breaking changes across versions.

One thing is probably still open here. `instanceId` propagation for the `*DataSource` classes. As it works for JDBC URLs only right now.

Anyway, the concept of url specific properties requires implementation to be provided per property => we can migrate later those, that would make sence. Still, `instanceId` should provide concept here.

@quintonm comments/objections?
Could we not use URL parameters?  We are already rewriting the JDBC URL to get the real driver anyway.  We could remove any P6Spy specific parameters so that they would not be passed to the real driver.