test_runner does not find checks in subdirectories

[Pitterling]

testrunner searches for *_test.sh files only in local directory.

Test in subdirectories should also be executed.

[Pitterling]

haven't found any easy to implement solution so far

have adjusted the command-line as a workaround

  bash -c 'cd ./scripts/tests/; ./test_runner'
  bash -c 'cd ./scripts/tests/; ./test_runner -t "$(echo ./check/*_test.sh)"'