print elasticsearch version

close #5664

also enhance test README

tests are not allowed to fail anymore.

caching cubrid breaks the build on a regular basis and has nearly no speedup

- Moved everything test-related into `tests` directory. Codeception tests are in `codeception`.
- Removed database module since we're using fixtures and migrations.
- Moved console entry points and bootstrap into `tests/codeception/bin`.
- Adjusted travis build scripts.
- Adjusted documentation to be consistent and reflect changes made.