sample-app testcases should run at once with multiple DBs

as we evolve, we need to make sure mvn test should run the same testcases in multiple db's once after the other, this can give confidence that, while working one db, other db is not compromised.

sample-app was working once with postgress, now that also not working.. (could be some local config issue too..), in any case we must make sure same tests run well every DB we support.
