Refactor Launchpad::Interaction#close test

- just test that it calls #stop
- test what #stop does in #stop tests
Add logging facilities
Add debugger to development dependencies
Add some debug/error logging
Refactor internal method name
Refactor code branches to map lookups

This results in less complex code but I'm not sure about the performance impact of this.
Rework multi threading
Clarify docs
Activate tests on 1.8.7