Adding hammer-tests

Execution of hammer tests from bats.
https://github.com/tstrachota/hammer-tests.git
When there's some unexpected error (e.g.ruby syntax) in the tests it goes to `stderr`. Hammer tests produce output to `stdout` which messes with `stderr` and makes the error difficult to read. Therefore I redirected it to `/dev/null`. 
Full output of the tests is always captured in `/root/hammer_tests_logs/*`.