Use `ctest` or `make test` to run all tests.
With this it's also possible to run tests on a Mac.
Relative paths used in tests become absolute ones to make tests
executable from any build folder.
Also fixed race condition in
test/broker/11-persistent-subscription-no-local.py
Signed-off-by: Kai Buschulte <kai.buschulte@cedalo.com>