test: create first draft of an integration test

The test creates a Vagrant VM, installs and configures Openlava (current
version of the open-sourced branch of Platform LSF; which uses no less
than 8 configuration files). Then the test runs one LSF job (which
currently fails because Ketrew uses `bjobs` options that Openlava does
not support).
test: remove function `ssh_for_root_to_root`
lib: add the `success_triggers` field
test: create `Happenings` and add triggering case
lib: integrate success-triggers in the UI
doc: add success-triggers to the `README.md`
Merge branch `dev` into `integration`
test: use success-triggers in integration test
lib: fix missing imports of success-triggers
Merge integration-testing branch into `dev`

The integration test still fails because of issue #15 but the test
itself is good.