Fix for #1637

This PR fixes the transaction support for getters within a association set method for 1-to-1 associations. Furthermore it sets the first steps for the sql event to take not only the sql query itself as the first parameter but also the connections identifier as a second one. In an upcoming PR I will change all currently manually captured sql events to use the proxy method of the customeventemitter. By doing that change, it always correctly pass the connection identifier to the sql event.